diff --git a/src/components/gfx/compositor.rs b/src/components/gfx/compositor.rs
index 742894f739a..ea87d548661 100644
--- a/src/components/gfx/compositor.rs
+++ b/src/components/gfx/compositor.rs
@@ -12,6 +12,8 @@ pub struct LayerBuffer {
     // The rect in the containing RenderLayer that this represents.
     rect: Rect<uint>,
 
+    screen_pos: Rect<uint>,
+
     // NB: stride is in pixels, like OpenGL GL_UNPACK_ROW_LENGTH.
     stride: uint
 }
@@ -22,9 +24,17 @@ pub struct LayerBufferSet {
     buffers: ~[LayerBuffer]
 }
 
+/// The status of the renderer.
+#[deriving(Eq)]
+pub enum RenderState {
+    IdleRenderState,
+    RenderingRenderState,
+}
+
 /// The interface used to by the renderer to acquire draw targets for each rendered frame and
 /// submit them to be drawn to the display.
 pub trait Compositor {
     fn paint(&self, layer_buffer_set: LayerBufferSet, new_size: Size2D<uint>);
+    fn set_render_state(&self, render_state: RenderState);
 }
 
diff --git a/src/components/gfx/font.rs b/src/components/gfx/font.rs
index 6405c0f34cb..3cc65061105 100644
--- a/src/components/gfx/font.rs
+++ b/src/components/gfx/font.rs
@@ -18,6 +18,8 @@ use azure::scaled_font::ScaledFont;
 use azure::azure_hl::{BackendType, ColorPattern};
 use geom::{Point2D, Rect, Size2D};
 
+use servo_util::time::ProfilerChan;
+
 // FontHandle encapsulates access to the platform's font API,
 // e.g. quartz, FreeType. It provides access to metrics and tables
 // needed by the text shaper as well as access to the underlying font
@@ -210,13 +212,15 @@ pub struct Font {
     style: UsedFontStyle,
     metrics: FontMetrics,
     backend: BackendType,
+    profiler_chan: ProfilerChan,
 }
 
 pub impl Font {
     fn new_from_buffer(ctx: &FontContext,
                        buffer: ~[u8],
                        style: &SpecifiedFontStyle,
-                       backend: BackendType)
+                       backend: BackendType,
+                       profiler_chan: ProfilerChan)
             -> Result<@mut Font, ()> {
         let handle = FontHandleMethods::new_from_buffer(&ctx.handle, buffer, style);
         let handle: FontHandle = if handle.is_ok() {
@@ -235,11 +239,13 @@ pub impl Font {
             style: copy *style,
             metrics: metrics,
             backend: backend,
+            profiler_chan: profiler_chan,
         });
     }
 
     fn new_from_adopted_handle(_fctx: &FontContext, handle: FontHandle,
-                               style: &SpecifiedFontStyle, backend: BackendType) -> @mut Font {
+                               style: &SpecifiedFontStyle, backend: BackendType,
+                               profiler_chan: ProfilerChan) -> @mut Font {
         let metrics = handle.get_metrics();
 
         @mut Font {
@@ -249,11 +255,13 @@ pub impl Font {
             style: copy *style,
             metrics: metrics,
             backend: backend,
+            profiler_chan: profiler_chan,
         }
     }
 
     fn new_from_existing_handle(fctx: &FontContext, handle: &FontHandle,
-                                style: &SpecifiedFontStyle, backend: BackendType) -> Result<@mut Font,()> {
+                                style: &SpecifiedFontStyle, backend: BackendType,
+                                profiler_chan: ProfilerChan) -> Result<@mut Font,()> {
 
         // TODO(Issue #179): convert between specified and used font style here?
         let styled_handle = match handle.clone_with_style(&fctx.handle, style) {
@@ -261,7 +269,7 @@ pub impl Font {
             Err(()) => return Err(())
         };
 
-        return Ok(Font::new_from_adopted_handle(fctx, styled_handle, style, backend));
+        return Ok(Font::new_from_adopted_handle(fctx, styled_handle, style, backend, profiler_chan));
     }
 
     priv fn get_shaper(@mut self) -> @Shaper {
diff --git a/src/components/gfx/font_context.rs b/src/components/gfx/font_context.rs
index e954d3e07ed..310b75944e5 100644
--- a/src/components/gfx/font_context.rs
+++ b/src/components/gfx/font_context.rs
@@ -40,17 +40,18 @@ pub struct FontContext {
     handle: FontContextHandle,
     backend: BackendType,
     generic_fonts: HashMap<~str,~str>,
+    profiler_chan: ProfilerChan,
 }
 
 #[allow(non_implicitly_copyable_typarams)]
 pub impl<'self> FontContext {
     fn new(backend: BackendType,
            needs_font_list: bool,
-           prof_chan: ProfilerChan)
+           profiler_chan: ProfilerChan)
            -> FontContext {
         let handle = FontContextHandle::new();
         let font_list = if needs_font_list { 
-                            Some(FontList::new(&handle, prof_chan.clone())) }
+                            Some(FontList::new(&handle, profiler_chan.clone())) }
                         else { None };
 
         // TODO: Allow users to specify these.
@@ -69,6 +70,7 @@ pub impl<'self> FontContext {
             handle: handle,
             backend: backend,
             generic_fonts: generic_fonts,
+            profiler_chan: profiler_chan,
         }
     }
 
@@ -125,7 +127,8 @@ pub impl<'self> FontContext {
             for result.each |font_entry| {
                 found = true;
                 // TODO(Issue #203): route this instantion through FontContext's Font instance cache.
-                let instance = Font::new_from_existing_handle(self, &font_entry.handle, style, self.backend);
+                let instance = Font::new_from_existing_handle(self, &font_entry.handle, style, self.backend,
+                                                              self.profiler_chan.clone());
                 do result::iter(&instance) |font: &@mut Font| { fonts.push(*font); }
             };
 
@@ -139,8 +142,14 @@ pub impl<'self> FontContext {
         for last_resort.each |family| {
             let result = list.find_font_in_family(*family,style);
             for result.each |font_entry| {
-                let instance = Font::new_from_existing_handle(self, &font_entry.handle, style, self.backend);
-                do result::iter(&instance) |font: &@mut Font| { fonts.push(*font); }
+                let instance = Font::new_from_existing_handle(self,
+                                                              &font_entry.handle,
+                                                              style,
+                                                              self.backend,
+                                                              self.profiler_chan.clone());
+                do result::iter(&instance) |font: &@mut Font| {
+                    fonts.push(*font);
+                }
             }
         }
 
@@ -163,7 +172,8 @@ pub impl<'self> FontContext {
                     Ok(Font::new_from_adopted_handle(self,
                                                      handle,
                                                      &desc.style,
-                                                     self.backend))
+                                                     self.backend,
+                                                     self.profiler_chan.clone()))
                 })
             }
         };
diff --git a/src/components/gfx/opts.rs b/src/components/gfx/opts.rs
index d9c6ff1446c..07c38f9a1bf 100644
--- a/src/components/gfx/opts.rs
+++ b/src/components/gfx/opts.rs
@@ -13,6 +13,11 @@ pub struct Opts {
     render_backend: BackendType,
     n_render_threads: uint,
     tile_size: uint,
+    profiler_period: Option<f64>,
+
+    /// A scale factor to apply to tiles, to allow rendering tiles at higher resolutions for
+    /// testing pan and zoom code.
+    zoom: uint,
 }
 
 #[allow(non_implicitly_copyable_typarams)]
@@ -26,13 +31,14 @@ pub fn from_cmdline_args(args: &[~str]) -> Opts {
         getopts::optopt(~"r"),  // rendering backend
         getopts::optopt(~"s"),  // size of tiles
         getopts::optopt(~"t"),  // threads to render with
+        getopts::optflagopt(~"p"),  // profiler flag and output interval
+        getopts::optopt(~"z"),  // zoom level
     ];
 
     let opt_match = match getopts::getopts(args, opts) {
       result::Ok(m) => { copy m }
       result::Err(f) => { fail!(getopts::fail_str(copy f)) }
     };
-
     let urls = if opt_match.free.is_empty() {
         fail!(~"servo asks that you provide 1 or more URLs")
     } else {
@@ -68,10 +74,24 @@ pub fn from_cmdline_args(args: &[~str]) -> Opts {
         None => 1,      // FIXME: Number of cores.
     };
 
+    let profiler_period: Option<f64> =
+        // if only flag is present, default to 5 second period
+        match getopts::opt_default(&opt_match, ~"p", ~"5") {
+        Some(period) => Some(f64::from_str(period).get()),
+        None => None,
+    };
+
+    let zoom: uint = match getopts::opt_maybe_str(&opt_match, ~"z") {
+        Some(zoom_str) => uint::from_str(zoom_str).get(),
+        None => 1,
+    };
+
     Opts {
         urls: urls,
         render_backend: render_backend,
         n_render_threads: n_render_threads,
         tile_size: tile_size,
+        profiler_period: profiler_period,
+        zoom: zoom,
     }
 }
diff --git a/src/components/gfx/render_layers.rs b/src/components/gfx/render_layers.rs
index a2cab09e2c1..a0741480dd7 100644
--- a/src/components/gfx/render_layers.rs
+++ b/src/components/gfx/render_layers.rs
@@ -37,6 +37,7 @@ pub fn render_layers(layer_ref: *RenderLayer,
                      f: RenderFn)
                      -> LayerBufferSet {
     let tile_size = opts.tile_size;
+    let scale = opts.zoom;
 
     // FIXME: Try not to create a new array here.
     let mut new_buffer_ports = ~[];
@@ -45,12 +46,12 @@ pub fn render_layers(layer_ref: *RenderLayer,
     do time::profile(time::RenderingPrepBuffCategory, prof_chan.clone()) {
         let layer: &RenderLayer = unsafe { cast::transmute(layer_ref) };
         let mut y = 0;
-        while y < layer.size.height {
+        while y < layer.size.height * scale {
             let mut x = 0;
-            while x < layer.size.width {
+            while x < layer.size.width * scale {
                 // Figure out the dimension of this tile.
-                let right = uint::min(x + tile_size, layer.size.width);
-                let bottom = uint::min(y + tile_size, layer.size.height);
+                let right = uint::min(x + tile_size, layer.size.width * scale);
+                let bottom = uint::min(y + tile_size, layer.size.height * scale);
                 let width = right - x;
                 let height = bottom - y;
 
@@ -65,7 +66,8 @@ pub fn render_layers(layer_ref: *RenderLayer,
 
                 debug!("tile aligned_width %u", aligned_width);
 
-                let tile_rect = Rect(Point2D(x, y), Size2D(aligned_width, height));
+                let tile_rect = Rect(Point2D(x / scale, y / scale), Size2D(aligned_width, height)); //change this
+                let screen_rect = Rect(Point2D(x, y), Size2D(aligned_width, height)); //change this
 
                 let buffer;
                 // FIXME: Try harder to search for a matching tile.
@@ -112,6 +114,7 @@ pub fn render_layers(layer_ref: *RenderLayer,
                                                                stride,
                                                                B8G8R8A8),
                         rect: tile_rect,
+                        screen_pos: screen_rect,
                         stride: stride as uint
                     };
                 //}
diff --git a/src/components/gfx/render_task.rs b/src/components/gfx/render_task.rs
index 2beabee6641..4b76e2ac0f6 100644
--- a/src/components/gfx/render_task.rs
+++ b/src/components/gfx/render_task.rs
@@ -5,7 +5,7 @@
 // The task that handles all rendering/painting.
 
 use azure::AzFloat;
-use compositor::Compositor;
+use compositor::{Compositor, IdleRenderState, RenderingRenderState};
 use font_context::FontContext;
 use geom::matrix2d::Matrix2D;
 use opts::Opts;
@@ -18,9 +18,7 @@ use core::task::SingleThreaded;
 use std::task_pool::TaskPool;
 use servo_net::util::spawn_listener;
 
-use servo_util::time::ProfilerChan;
-use servo_util::time::profile;
-use servo_util::time::time;
+use servo_util::time::{ProfilerChan, profile};
 use servo_util::time;
 
 pub enum Msg {
@@ -124,7 +122,8 @@ impl<C: Compositor + Owned> Renderer<C> {
 
     fn render(&mut self, render_layer: RenderLayer) {
         debug!("renderer: rendering");
-        do time("rendering") {
+        self.compositor.set_render_state(RenderingRenderState);
+        do profile(time::RenderingCategory, self.profiler_chan.clone()) {
             let layer_buffer_set = do render_layers(&render_layer,
                                                     &self.opts,
                                                     self.profiler_chan.clone()) |render_layer_ref,
@@ -142,17 +141,24 @@ impl<C: Compositor + Owned> Renderer<C> {
 
                         // Apply the translation to render the tile we want.
                         let matrix: Matrix2D<AzFloat> = Matrix2D::identity();
-                        let matrix = matrix.translate(&-(layer_buffer.rect.origin.x as AzFloat),
-                                                      &-(layer_buffer.rect.origin.y as AzFloat));
+                        let scale = thread_render_context.opts.zoom as f32;
+
+                        let matrix = matrix.scale(scale as AzFloat, scale as AzFloat);
+                        let matrix = matrix.translate(-(layer_buffer.rect.origin.x as f32) as AzFloat,
+                                                      -(layer_buffer.rect.origin.y as f32) as AzFloat);
+
+
                         layer_buffer.draw_target.set_transform(&matrix);
 
                         // Clear the buffer.
                         ctx.clear();
+                        
 
                         // Draw the display list.
                         let render_layer: &RenderLayer = unsafe {
                             cast::transmute(render_layer_ref)
                         };
+                        
                         render_layer.display_list.draw_into_context(&ctx);
                     }
 
@@ -163,6 +169,7 @@ impl<C: Compositor + Owned> Renderer<C> {
 
             debug!("renderer: returning surface");
             self.compositor.paint(layer_buffer_set, render_layer.size);
+            self.compositor.set_render_state(IdleRenderState);
         }
     }
 }
diff --git a/src/components/gfx/text/text_run.rs b/src/components/gfx/text/text_run.rs
index 3778e4353db..905371488dc 100644
--- a/src/components/gfx/text/text_run.rs
+++ b/src/components/gfx/text/text_run.rs
@@ -6,6 +6,8 @@ use font_context::FontContext;
 use geometry::Au;
 use text::glyph::{BreakTypeNormal, GlyphStore};
 use font::{Font, FontDescriptor, RunMetrics};
+use servo_util::time;
+use servo_util::time::profile;
 use servo_util::range::Range;
 
 /// A text run.
@@ -44,7 +46,9 @@ pub impl<'self> TextRun {
     fn new(font: @mut Font, text: ~str, underline: bool) -> TextRun {
         let mut glyph_store = GlyphStore::new(str::char_len(text));
         TextRun::compute_potential_breaks(text, &mut glyph_store);
-        font.shape_text(text, &mut glyph_store);
+        do profile(time::LayoutShapingCategory, font.profiler_chan.clone()) {
+            font.shape_text(text, &mut glyph_store);
+        }
 
         let run = TextRun {
             text: text,
diff --git a/src/components/main/compositing/mod.rs b/src/components/main/compositing/mod.rs
index c0b08be2f15..452f4bbb06d 100644
--- a/src/components/main/compositing/mod.rs
+++ b/src/components/main/compositing/mod.rs
@@ -5,8 +5,13 @@
 use compositing::resize_rate_limiter::ResizeRateLimiter;
 use platform::{Application, Window};
 use script::script_task::{LoadMsg, ScriptMsg, SendEventMsg};
-use windowing::{ApplicationMethods, WindowMethods};
-use script::dom::event::ClickEvent;
+use windowing::{ApplicationMethods, WindowMethods, WindowMouseEvent, WindowClickEvent};
+use windowing::{WindowMouseDownEvent, WindowMouseUpEvent};
+
+use gfx::compositor::RenderState;
+use script::dom::event::{Event, ClickEvent, MouseDownEvent, MouseUpEvent};
+use script::compositor_interface::{ReadyState, CompositorInterface};
+use script::compositor_interface;
 
 use azure::azure_hl::{DataSourceSurface, DrawTarget, SourceSurfaceMethods};
 use core::cell::Cell;
@@ -16,7 +21,7 @@ use core::util;
 use geom::matrix::identity;
 use geom::point::Point2D;
 use geom::size::Size2D;
-use gfx::compositor::{Compositor, LayerBufferSet};
+use gfx::compositor::{Compositor, LayerBufferSet, RenderState};
 use layers::layers::{ARGB32Format, BasicImageData, ContainerLayer, ContainerLayerKind, Format};
 use layers::layers::{Image, ImageData, ImageLayer, ImageLayerKind, RGB24Format, WithDataFn};
 use layers::rendergl;
@@ -34,11 +39,17 @@ pub struct CompositorTask {
     chan: SharedChan<Msg>,
 }
 
+impl CompositorInterface for CompositorTask {
+    fn set_ready_state(&self, ready_state: ReadyState) {
+        let msg = ChangeReadyState(ready_state);
+        self.chan.send(msg);
+    }
+}
+
 impl CompositorTask {
     /// Starts the compositor. Returns an interface that can be used to communicate with the
     /// compositor and a port which allows notification when the compositor shuts down.
-    pub fn new(script_chan: SharedChan<ScriptMsg>,
-               profiler_chan: ProfilerChan)
+    pub fn new(script_chan: SharedChan<ScriptMsg>, profiler_chan: ProfilerChan)
                -> (CompositorTask, Port<()>) {
         let script_chan = Cell(script_chan);
         let (shutdown_port, shutdown_chan) = stream();
@@ -61,10 +72,14 @@ impl CompositorTask {
 
 /// Messages to the compositor.
 pub enum Msg {
-    /// Requests that the compositor paint the given layer buffer set for the given page size.
-    Paint(LayerBufferSet, Size2D<uint>),
     /// Requests that the compositor shut down.
     Exit,
+    /// Requests that the compositor paint the given layer buffer set for the given page size.
+    Paint(LayerBufferSet, Size2D<uint>),
+    /// Alerts the compositor to the current status of page loading.
+    ChangeReadyState(ReadyState),
+    /// Alerts the compositor to the current status of rendering.
+    ChangeRenderState(RenderState),
 }
 
 /// Azure surface wrapping to work with the layers infrastructure.
@@ -126,15 +141,20 @@ fn run_main_loop(port: Port<Msg>,
     let page_size = @mut Size2D(0f32, 0f32);
     let window_size = @mut Size2D(800, 600);
 
+    // Keeps track of the current zoom factor
+    let world_zoom = @mut 1f32;
+
     let check_for_messages: @fn() = || {
         // Periodically check if the script task responded to our last resize event
         resize_rate_limiter.check_resize_response();
-
         // Handle messages
         while port.peek() {
             match port.recv() {
                 Exit => *done = true,
 
+                ChangeReadyState(ready_state) => window.set_ready_state(ready_state),
+                ChangeRenderState(render_state) => window.set_render_state(render_state),
+
                 Paint(new_layer_buffer_set, new_size) => {
                     debug!("osmain: received new frame");
 
@@ -183,7 +203,7 @@ fn run_main_loop(port: Port<Msg>,
                             Some(_) => fail!(~"found unexpected layer kind"),
                         };
 
-                        let origin = buffer.rect.origin;
+                        let origin = buffer.screen_pos.origin;
                         let origin = Point2D(origin.x as f32, origin.y as f32);
 
                         // Set the layer's transform.
@@ -233,12 +253,24 @@ fn run_main_loop(port: Port<Msg>,
 
     let script_chan_clone = script_chan.clone();
 
-    // When the user clicks, perform hit testing
-    do window.set_click_callback |layer_click_point| {
-        let world_click_point = layer_click_point + *world_offset;
-        debug!("osmain: clicked at %?", world_click_point);
-
-        script_chan_clone.send(SendEventMsg(ClickEvent(world_click_point)));
+    // When the user triggers a mouse event, perform appropriate hit testing
+    do window.set_mouse_callback |window_mouse_event: WindowMouseEvent| {
+        let event: Event;
+        let world_mouse_point = |layer_mouse_point: Point2D<f32>| {
+            layer_mouse_point + *world_offset
+        };
+        match window_mouse_event {
+            WindowClickEvent(button, layer_mouse_point) => {
+                event = ClickEvent(button, world_mouse_point(layer_mouse_point));
+            }
+            WindowMouseDownEvent(button, layer_mouse_point) => {
+                event = MouseDownEvent(button, world_mouse_point(layer_mouse_point));
+            }
+            WindowMouseUpEvent(button, layer_mouse_point) => {
+                event = MouseUpEvent(button, world_mouse_point(layer_mouse_point));
+            }
+        }
+        script_chan_clone.send(SendEventMsg(event));
     }
 
     // When the user scrolls, move the layer around.
@@ -248,16 +280,64 @@ fn run_main_loop(port: Port<Msg>,
         *world_offset = world_offset_copy - delta;
 
         // Clamp the world offset to the screen size.
-        let max_x = (page_size.width - window_size.width as f32).max(&0.0);
+        let max_x = (page_size.width * *world_zoom - window_size.width as f32).max(&0.0);
         world_offset.x = world_offset.x.clamp(&0.0, &max_x);
-        let max_y = (page_size.height - window_size.height as f32).max(&0.0);
+        let max_y = (page_size.height * *world_zoom - window_size.height as f32).max(&0.0);
         world_offset.y = world_offset.y.clamp(&0.0, &max_y);
 
         debug!("compositor: scrolled to %?", *world_offset);
 
-        root_layer.common.set_transform(identity().translate(-world_offset.x,
-                                                             -world_offset.y,
-                                                             0.0));
+        let mut scroll_transform = identity();
+
+        scroll_transform = scroll_transform.translate(window_size.width as f32 / 2f32 * *world_zoom - world_offset.x,
+                                                  window_size.height as f32 / 2f32 * *world_zoom - world_offset.y,
+                                                  0.0);
+        scroll_transform = scroll_transform.scale(*world_zoom, *world_zoom, 1f32);
+        scroll_transform = scroll_transform.translate(window_size.width as f32 / -2f32,
+                                                  window_size.height as f32 / -2f32,
+                                                  0.0);
+
+        root_layer.common.set_transform(scroll_transform);
+
+        window.set_needs_display()
+    }
+
+
+
+    // When the user pinch-zooms, scale the layer
+    do window.set_zoom_callback |magnification| {
+        let old_world_zoom = *world_zoom;
+
+        // Determine zoom amount
+        *world_zoom = (*world_zoom * magnification).max(&1.0);            
+
+        // Update world offset
+        let corner_to_center_x = world_offset.x + window_size.width as f32 / 2f32;
+        let new_corner_to_center_x = corner_to_center_x * *world_zoom / old_world_zoom;
+        world_offset.x = world_offset.x + new_corner_to_center_x - corner_to_center_x;
+
+        let corner_to_center_y = world_offset.y + window_size.height as f32 / 2f32;
+        let new_corner_to_center_y = corner_to_center_y * *world_zoom / old_world_zoom;
+        world_offset.y = world_offset.y + new_corner_to_center_y - corner_to_center_y;        
+
+        // Clamp to page bounds when zooming out
+        let max_x = (page_size.width * *world_zoom - window_size.width as f32).max(&0.0);
+        world_offset.x = world_offset.x.clamp(&0.0, &max_x);
+        let max_y = (page_size.height * *world_zoom - window_size.height as f32).max(&0.0);
+        world_offset.y = world_offset.y.clamp(&0.0, &max_y);
+
+
+        // Apply transformations
+        let mut zoom_transform = identity();
+        zoom_transform = zoom_transform.translate(window_size.width as f32 / 2f32 * *world_zoom - world_offset.x,
+                                                  window_size.height as f32 / 2f32 * *world_zoom - world_offset.y,
+                                                  0.0);
+        zoom_transform = zoom_transform.scale(*world_zoom, *world_zoom, 1f32);
+        zoom_transform = zoom_transform.translate(window_size.width as f32 / -2f32,
+                                                  window_size.height as f32 / -2f32,
+                                                  0.0);
+        root_layer.common.set_transform(zoom_transform);
+
 
         window.set_needs_display()
     }
@@ -279,6 +359,9 @@ impl Compositor for CompositorTask {
     fn paint(&self, layer_buffer_set: LayerBufferSet, new_size: Size2D<uint>) {
         self.chan.send(Paint(layer_buffer_set, new_size))
     }
+    fn set_render_state(&self, render_state: RenderState) {
+        self.chan.send(ChangeRenderState(render_state))
+    }
 }
 
 /// A function for spawning into the platform's main thread.
diff --git a/src/components/main/css/select.rs b/src/components/main/css/select.rs
index 46c62de20ea..7ebf2519ba9 100644
--- a/src/components/main/css/select.rs
+++ b/src/components/main/css/select.rs
@@ -124,6 +124,8 @@ ul, ol, dl    { page-break-before: avoid }
 
 /* Servo additions */
 :link           { color: blue }
+script          { display: none }
+style           { display: none }
 "
 }
 
diff --git a/src/components/main/engine.rs b/src/components/main/engine.rs
index 1d396c1a70f..921688bd061 100644
--- a/src/components/main/engine.rs
+++ b/src/components/main/engine.rs
@@ -4,13 +4,14 @@
 
 use compositing::CompositorTask;
 use layout::layout_task;
-use util::task::spawn_listener;
 
 use core::cell::Cell;
-use core::comm::{Chan, Port, SharedChan};
+use core::comm::{Port, SharedChan};
 use gfx::opts::Opts;
 use gfx::render_task::RenderTask;
 use gfx::render_task;
+use script::compositor_interface::{CompositorInterface, ReadyState};
+use script::engine_interface::{EngineTask, ExitMsg, LoadUrlMsg, Msg};
 use script::layout_interface::LayoutTask;
 use script::layout_interface;
 use script::script_task::{ExecuteMsg, LoadMsg, ScriptMsg, ScriptTask};
@@ -18,15 +19,7 @@ use script::script_task;
 use servo_net::image_cache_task::{ImageCacheTask, ImageCacheTaskClient};
 use servo_net::resource_task::ResourceTask;
 use servo_net::resource_task;
-use servo_util::time::{ProfilerChan, ProfilerPort, ProfilerTask};
-use std::net::url::Url;
-
-pub type EngineTask = Chan<Msg>;
-
-pub enum Msg {
-    LoadUrlMsg(Url),
-    ExitMsg(Chan<()>),
-}
+use servo_util::time::{ProfilerChan, ProfilerPort, ProfilerTask, ForcePrintMsg};
 
 pub struct Engine {
     request_port: Port<Msg>,
@@ -39,6 +32,12 @@ pub struct Engine {
     profiler_task: ProfilerTask,
 }
 
+impl Drop for Engine {
+    fn finalize(&self) {
+        self.profiler_task.chan.send(ForcePrintMsg);
+    }
+}
+
 impl Engine {
     pub fn start(compositor: CompositorTask,
                  opts: &Opts,
@@ -50,31 +49,44 @@ impl Engine {
                  profiler_chan: ProfilerChan)
                  -> EngineTask {
         let (script_port, script_chan) = (Cell(script_port), Cell(script_chan));
+        let (engine_port, engine_chan) = comm::stream();
+        let (engine_port, engine_chan) = (Cell(engine_port), SharedChan::new(engine_chan));
+        let engine_chan_clone = engine_chan.clone();
+        let compositor = Cell(compositor);
         let profiler_port = Cell(profiler_port);
         let opts = Cell(copy *opts);
 
-        do spawn_listener::<Msg> |request| {
+        do task::spawn {
+            let compositor = compositor.take();
             let render_task = RenderTask::new(compositor.clone(),
                                               opts.with_ref(|o| copy *o),
                                               profiler_chan.clone());
 
-            let profiler_task = ProfilerTask::new(profiler_port.take(), profiler_chan.clone());
-
             let opts = opts.take();
+
+            let profiler_task = ProfilerTask::new(profiler_port.take(),
+                                                  profiler_chan.clone(),
+                                                  opts.profiler_period);
+
             let layout_task = layout_task::create_layout_task(render_task.clone(),
                                                               image_cache_task.clone(),
                                                               opts,
                                                               profiler_task.chan.clone());
 
+            let compositor_clone = compositor.clone();
             let script_task = ScriptTask::new(script_port.take(),
                                               script_chan.take(),
+                                              engine_chan_clone.clone(),
+                                              |msg: ReadyState| {
+                                                  compositor_clone.set_ready_state(msg)
+                                              },
                                               layout_task.clone(),
                                               resource_task.clone(),
                                               image_cache_task.clone());
 
 
             Engine {
-                request_port: request,
+                request_port: engine_port.take(),
                 compositor: compositor.clone(),
                 render_task: render_task,
                 resource_task: resource_task.clone(),
@@ -82,8 +94,9 @@ impl Engine {
                 layout_task: layout_task,
                 script_task: script_task,
                 profiler_task: profiler_task,
-            }.run()
+            }.run();
         }
+        engine_chan.clone()
     }
 
     fn run(&self) {
diff --git a/src/components/main/layout/block.rs b/src/components/main/layout/block.rs
index fc90d3273d2..f7f07b14df2 100644
--- a/src/components/main/layout/block.rs
+++ b/src/components/main/layout/block.rs
@@ -196,21 +196,20 @@ impl BlockFlowData {
                 let available_width = remaining_width - model.noncontent_width();
 
                 // Top and bottom margins for blocks are 0 if auto.
-                let margin_top = MaybeAuto::from_margin(style.margin_top());
-                let margin_top = margin_top.spec_or_default(Au(0));
-                let margin_bottom = MaybeAuto::from_margin(style.margin_bottom());
-                let margin_bottom = margin_bottom.spec_or_default(Au(0));
+                let margin_top = MaybeAuto::from_margin(style.margin_top(),
+                                                        remaining_width).spec_or_default(Au(0));
+                let margin_bottom = MaybeAuto::from_margin(style.margin_bottom(),
+                                                           remaining_width).spec_or_default(Au(0));
 
                 let (width, margin_left, margin_right) =
-                    (MaybeAuto::from_width(style.width()),
-                     MaybeAuto::from_margin(style.margin_left()),
-                     MaybeAuto::from_margin(style.margin_right()));
+                    (MaybeAuto::from_width(style.width(), remaining_width),
+                     MaybeAuto::from_margin(style.margin_left(), remaining_width),
+                     MaybeAuto::from_margin(style.margin_right(), remaining_width));
 
-                // FIXME(pcwalton): We discard the width here. Is that correct?
-                let (_, margin_left, margin_right) = self.compute_horiz(width,
-                                                                        margin_left,
-                                                                        margin_right,
-                                                                        available_width);
+                let (width, margin_left, margin_right) = self.compute_horiz(width,
+                                                                            margin_left,
+                                                                            margin_right,
+                                                                            available_width);
 
                 model.margin.top = margin_top;
                 model.margin.right = margin_right;
@@ -218,7 +217,7 @@ impl BlockFlowData {
                 model.margin.left = margin_left;
 
                 x_offset = model.offset();
-                remaining_width = remaining_width - model.noncontent_width();
+                remaining_width = width;
             }
 
             do box.with_mut_base |base| {
@@ -243,10 +242,12 @@ impl BlockFlowData {
 
     pub fn assign_height_block(@mut self, ctx: &LayoutContext) {
         let mut cur_y = Au(0);
+        let mut top_offset = Au(0);
 
         for self.box.each |&box| {
             do box.with_model |model| {
-                cur_y += model.margin.top + model.border.top + model.padding.top;
+                top_offset = model.margin.top + model.border.top + model.padding.top;
+                cur_y += top_offset;
             }
         }
 
@@ -260,22 +261,26 @@ impl BlockFlowData {
         let height = if self.is_root {
             Au::max(ctx.screen_size.size.height, cur_y)
         } else {
-            cur_y
+            cur_y - top_offset
         };
-
-        //TODO(eatkinson): compute heights using the 'height' property.
-        self.common.position.size.height = height;
-
+        
+        let mut noncontent_height = Au(0);
         self.box.map(|&box| {
             do box.with_mut_base |base| {
                 //The associated box is the border box of this flow
                 base.position.origin.y = base.model.margin.top;
 
-                let pb = base.model.padding.top + base.model.padding.bottom +
+                noncontent_height = base.model.padding.top + base.model.padding.bottom +
                     base.model.border.top + base.model.border.bottom;
-                base.position.size.height = height + pb;
+                base.position.size.height = height + noncontent_height;
+
+                noncontent_height += base.model.margin.top + base.model.margin.bottom;
             }
         });
+
+        //TODO(eatkinson): compute heights using the 'height' property.
+        self.common.position.size.height = height + noncontent_height;
+
     }
 
     pub fn build_display_list_block<E:ExtraDisplayListData>(@mut self,
diff --git a/src/components/main/layout/box.rs b/src/components/main/layout/box.rs
index 78934a937b4..48b5ede54c8 100644
--- a/src/components/main/layout/box.rs
+++ b/src/components/main/layout/box.rs
@@ -627,19 +627,20 @@ pub impl RenderBox {
             },
 
             GenericRenderBoxClass(_) => {
+                // FIXME(pcwalton): This is somewhat of an abuse of the logging system.
                 debug!("%?", { 
-                // Compute the text box bounds and draw a border surrounding them.
-                do list.with_mut_ref |list| {
-                    let border_display_item = ~BorderDisplayItem {
-                        base: BaseDisplayItem {
-                            bounds: absolute_box_bounds,
-                            extra: ExtraDisplayListData::new(*self),
-                        },
-                        width: Au::from_px(1),
-                        color: rgb(0, 0, 0).to_gfx_color(),
-                    };
+                    // Compute the text box bounds and draw a border surrounding them.
+                    do list.with_mut_ref |list| {
+                        let border_display_item = ~BorderDisplayItem {
+                            base: BaseDisplayItem {
+                                    bounds: absolute_box_bounds,
+                                    extra: ExtraDisplayListData::new(*self),
+                            },
+                            width: Au::from_px(1),
+                            color: rgb(0, 0, 0).to_gfx_color(),
+                        };
                         list.append_item(BorderDisplayItemClass(border_display_item))
-                }
+                    }
                 });
             }
 
diff --git a/src/components/main/layout/box_builder.rs b/src/components/main/layout/box_builder.rs
index 99153d51ee4..b446f8a7172 100644
--- a/src/components/main/layout/box_builder.rs
+++ b/src/components/main/layout/box_builder.rs
@@ -451,7 +451,7 @@ pub impl LayoutTreeBuilder {
                 let first_child = do parent_flow.with_base |parent_node| {
                     parent_node.first_child
                 };
-                for first_child.each |first_flow| {
+                for first_child.each |&first_flow| {
                     if first_flow.starts_inline_flow() {
                         // FIXME: workaround for rust#6393
                         let mut do_remove = false;
@@ -466,7 +466,7 @@ pub impl LayoutTreeBuilder {
                             }
                         }
                         if (do_remove) { 
-                            (*parent_flow).remove_child(*first_flow);
+                            (*parent_flow).remove_child(first_flow);
                         }
                     }
                 }
@@ -474,7 +474,7 @@ pub impl LayoutTreeBuilder {
                 let last_child = do parent_flow.with_base |parent_node| {
                     parent_node.last_child
                 };
-                for last_child.each |last_flow| {
+                for last_child.each |&last_flow| {
                     if last_flow.starts_inline_flow() {
                         // FIXME: workaround for rust#6393
                         let mut do_remove = false;
@@ -489,7 +489,7 @@ pub impl LayoutTreeBuilder {
                             }
                         }
                         if (do_remove) {
-                            (*parent_flow).remove_child(*last_flow);
+                            (*parent_flow).remove_child(last_flow);
                         }
                     }
                 }
diff --git a/src/components/main/layout/layout_task.rs b/src/components/main/layout/layout_task.rs
index 385014a1172..9b896c1253e 100644
--- a/src/components/main/layout/layout_task.rs
+++ b/src/components/main/layout/layout_task.rs
@@ -38,7 +38,7 @@ use script::layout_interface::{ContentBoxesQuery, ContentBoxesResponse, ExitMsg,
 use script::layout_interface::{LayoutResponse, LayoutTask, MatchSelectorsDocumentDamage, Msg};
 use script::layout_interface::{QueryMsg, Reflow, ReflowDocumentDamage, ReflowForDisplay};
 use script::layout_interface::{ReflowMsg};
-use script::script_task::{ScriptMsg, SendEventMsg};
+use script::script_task::{ReflowCompleteMsg, ScriptMsg, SendEventMsg};
 use servo_net::image_cache_task::{ImageCacheTask, ImageResponseMsg};
 use servo_net::local_image_cache::LocalImageCache;
 use servo_util::tree::{TreeNodeRef, TreeUtils};
@@ -255,7 +255,11 @@ impl Layout {
         debug!("%?", layout_root.dump());
 
         // Tell script that we're done.
+        //
+        // FIXME(pcwalton): This should probably be *one* channel, but we can't fix this without
+        // either select or a filtered recv() that only looks for messages of a given type.
         data.script_join_chan.send(());
+        data.script_chan.send(ReflowCompleteMsg);
     }
 
     /// Handles a query from the script task. This is the main routine that DOM functions like
@@ -342,13 +346,14 @@ impl Layout {
                         flow.build_display_list(&builder,
                                                 &flow.position(),
                                                 display_list);
-                        // iterate in reverse to ensure we have the most recently painted render box
                         let (x, y) = (Au::from_frac_px(point.x as float),
                                       Au::from_frac_px(point.y as float));
                         let mut resp = Err(());
                         let display_list = &display_list.take().list;
+                        // iterate in reverse to ensure we have the most recently painted render box
                         for display_list.each_reverse |display_item| {
                             let bounds = display_item.bounds();
+                            // TODO this check should really be performed by a method of DisplayItem
                             if x <= bounds.origin.x + bounds.size.width &&
                                bounds.origin.x <= x &&
                                y < bounds.origin.y + bounds.size.height &&
diff --git a/src/components/main/layout/model.rs b/src/components/main/layout/model.rs
index 0260fd346c7..37195aa757e 100644
--- a/src/components/main/layout/model.rs
+++ b/src/components/main/layout/model.rs
@@ -37,12 +37,12 @@ pub enum MaybeAuto {
     Specified(Au),
 }
 
-impl MaybeAuto {
-    pub fn from_margin(margin: CSSMargin) -> MaybeAuto{
+impl MaybeAuto{
+    pub fn from_margin(margin: CSSMargin, cb_width: Au) -> MaybeAuto{
         match margin {
             CSSMarginAuto => Auto,
             //FIXME(eatkinson): Compute percents properly
-            CSSMarginPercentage(_) => Specified(Au(0)),
+            CSSMarginPercentage(percent) => Specified(cb_width.scale_by(percent/100.0)),
             //FIXME(eatkinson): Compute pt and em values properly
             CSSMarginLength(Px(v)) | 
             CSSMarginLength(Pt(v)) | 
@@ -50,11 +50,10 @@ impl MaybeAuto {
         }
     }
 
-    pub fn from_width(width: CSSWidth) -> MaybeAuto{
+    pub fn from_width(width: CSSWidth, cb_width: Au) -> MaybeAuto{
         match width{
             CSSWidthAuto => Auto,
-            //FIXME(eatkinson): Compute percents properly
-            CSSWidthPercentage(_) => Specified(Au(0)),
+            CSSWidthPercentage(percent) => Specified(cb_width.scale_by(percent/100.0)),
             //FIXME(eatkinson): Compute pt and em values properly
             CSSWidthLength(Px(v)) | 
             CSSWidthLength(Pt(v)) | 
@@ -135,7 +134,7 @@ impl BoxModel {
                 // FIXME(eatkinson): Handle 'em' and 'pt' correctly
                 Au::from_frac_px(v)
             }
-            CSSPaddingPercentage(p) => content_box_width.scale_by(p)
+            CSSPaddingPercentage(p) => content_box_width.scale_by(p/100.0)
         }
     }
 }
@@ -165,12 +164,12 @@ impl RenderBox {
             let border_width = border.top;
             let bounds = Rect {
                 origin: Point2D {
-                    x: abs_bounds.origin.x,
-                    y: abs_bounds.origin.y,
+                    x: abs_bounds.origin.x + border_width.scale_by(0.5),
+                    y: abs_bounds.origin.y + border_width.scale_by(0.5),
                 },
                 size: Size2D {
-                    width: abs_bounds.size.width,
-                    height: abs_bounds.size.height
+                    width: abs_bounds.size.width - border_width,
+                    height: abs_bounds.size.height - border_width
                 }
             };
 
diff --git a/src/components/main/platform/common/glut_windowing.rs b/src/components/main/platform/common/glut_windowing.rs
index 07a2f3bf9c2..0b35f24ae7c 100644
--- a/src/components/main/platform/common/glut_windowing.rs
+++ b/src/components/main/platform/common/glut_windowing.rs
@@ -7,16 +7,22 @@
 /// GLUT is a very old and bare-bones toolkit. However, it has good cross-platform support, at
 /// least on desktops. It is designed for testing Servo without the need of a UI.
 
-use windowing::{ApplicationMethods, CompositeCallback, LoadUrlCallback, ClickCallback};
-use windowing::{ResizeCallback, ScrollCallback, WindowMethods};
+use windowing::{ApplicationMethods, CompositeCallback, LoadUrlCallback, MouseCallback};
+use windowing::{ResizeCallback, ScrollCallback, WindowMethods, WindowMouseEvent, WindowClickEvent};
+use windowing::{WindowMouseDownEvent, WindowMouseUpEvent, ZoomCallback};
 
 use alert::{Alert, AlertMethods};
+use core::cell::Cell;
 use core::libc::c_int;
 use geom::point::Point2D;
 use geom::size::Size2D;
-use glut::glut::{DOUBLE, WindowHeight, WindowWidth};
+use gfx::compositor::{IdleRenderState, RenderState, RenderingRenderState};
+use glut::glut::{ACTIVE_CTRL, DOUBLE, HAVE_PRECISE_MOUSE_WHEEL, WindowHeight, WindowWidth};
 use glut::glut;
 use glut::machack;
+use script::compositor_interface::{FinishedLoading, Loading, PerformingLayout, ReadyState};
+
+static THROBBER: [char, ..8] = [ '⣾', '⣽', '⣻', '⢿', '⡿', '⣟', '⣯', '⣷' ];
 
 /// A structure responsible for setting up and tearing down the entire windowing system.
 pub struct Application;
@@ -36,10 +42,18 @@ pub struct Window {
     composite_callback: Option<CompositeCallback>,
     resize_callback: Option<ResizeCallback>,
     load_url_callback: Option<LoadUrlCallback>,
-    click_callback: Option<ClickCallback>,
+    mouse_callback: Option<MouseCallback>,
     scroll_callback: Option<ScrollCallback>,
+    zoom_callback: Option<ZoomCallback>,
 
     drag_origin: Point2D<c_int>,
+
+    mouse_down_button: @mut c_int,
+    mouse_down_point: @mut Point2D<c_int>,
+
+    ready_state: ReadyState,
+    render_state: RenderState,
+    throbber_frame: u8,
 }
 
 impl WindowMethods<Application> for Window {
@@ -56,10 +70,30 @@ impl WindowMethods<Application> for Window {
             composite_callback: None,
             resize_callback: None,
             load_url_callback: None,
-            click_callback: None,
+            mouse_callback: None,
             scroll_callback: None,
+            zoom_callback: None,
 
             drag_origin: Point2D(0, 0),
+
+            mouse_down_button: @mut 0,
+            mouse_down_point: @mut Point2D(0, 0),
+
+            ready_state: FinishedLoading,
+            render_state: IdleRenderState,
+            throbber_frame: 0,
+        };
+
+        // Spin the event loop every 50 ms to allow the Rust channels to be polled.
+        //
+        // This requirement is pretty much the nail in the coffin for GLUT's usefulness.
+        //
+        // FIXME(pcwalton): What a mess.
+        let register_timer_callback: @mut @fn() = @mut ||{};
+        *register_timer_callback = || {
+            glut::timer_func(50, *register_timer_callback);
+            window.throbber_frame = (window.throbber_frame + 1) % (THROBBER.len() as u8);
+            window.update_window_title()
         };
 
         // Register event handlers.
@@ -79,13 +113,25 @@ impl WindowMethods<Application> for Window {
         do glut::keyboard_func |key, _, _| {
             window.handle_key(key)
         }
-        do glut::mouse_func |button, _, x, y| {
+        do glut::mouse_func |button, state, x, y| {
             if button < 3 {
-                window.handle_click(x, y);
-            } else {
-                window.handle_scroll(if button == 4 { -30.0 } else { 30.0 });
+                window.handle_mouse(button, state, x, y);
             }
         }
+        do glut::mouse_wheel_func |wheel, direction, x, y| {
+            let delta = if HAVE_PRECISE_MOUSE_WHEEL {
+                (direction as f32) / 10000.0
+            } else {
+                (direction as f32) * 30.0
+            };
+
+            match wheel {
+                1 => window.handle_scroll(Point2D(delta, 0.0)),
+                2 => window.handle_zoom(delta),
+                _ => window.handle_scroll(Point2D(0.0, delta)),
+            }
+        }
+        (*register_timer_callback)();
 
         machack::perform_scroll_wheel_hack();
 
@@ -117,9 +163,9 @@ impl WindowMethods<Application> for Window {
         self.load_url_callback = Some(new_load_url_callback)
     }
 
-    /// Registers a callback to be run when a click event occurs.
-    pub fn set_click_callback(&mut self, new_click_callback: ClickCallback) {
-        self.click_callback = Some(new_click_callback)
+    /// Registers a callback to be run when a mouse event occurs.
+    pub fn set_mouse_callback(&mut self, new_mouse_callback: MouseCallback) {
+        self.mouse_callback = Some(new_mouse_callback)
     }
 
     /// Registers a callback to be run when the user scrolls.
@@ -127,6 +173,11 @@ impl WindowMethods<Application> for Window {
         self.scroll_callback = Some(new_scroll_callback)
     }
 
+    /// Registers a zoom to be run when the user zooms.
+    pub fn set_zoom_callback(&mut self, new_zoom_callback: ZoomCallback) {
+        self.zoom_callback = Some(new_zoom_callback)
+    }
+
     /// Spins the event loop.
     pub fn check_loop(@mut self) {
         glut::check_loop()
@@ -136,30 +187,110 @@ impl WindowMethods<Application> for Window {
     pub fn set_needs_display(@mut self) {
         glut::post_redisplay()
     }
+
+    /// Sets the ready state.
+    pub fn set_ready_state(@mut self, ready_state: ReadyState) {
+        self.ready_state = ready_state;
+        self.update_window_title()
+    }
+
+    /// Sets the render state.
+    pub fn set_render_state(@mut self, render_state: RenderState) {
+        self.render_state = render_state;
+        self.update_window_title()
+    }
 }
 
 impl Window {
+    /// Helper function to set the window title in accordance with the ready state.
+    fn update_window_title(&self) {
+        let throbber = THROBBER[self.throbber_frame];
+        match self.ready_state {
+            Loading => {
+                glut::set_window_title(self.glut_window, fmt!("%c Loading — Servo", throbber))
+            }
+            PerformingLayout => {
+                glut::set_window_title(self.glut_window,
+                                       fmt!("%c Performing Layout — Servo", throbber))
+            }
+            FinishedLoading => {
+                match self.render_state {
+                    RenderingRenderState => {
+                        glut::set_window_title(self.glut_window,
+                                               fmt!("%c Rendering — Servo", throbber))
+                    }
+                    IdleRenderState => glut::set_window_title(self.glut_window, "Servo"),
+                }
+            }
+        }
+    }
+
     /// Helper function to handle keyboard events.
     fn handle_key(&self, key: u8) {
         debug!("got key: %d", key as int);
-        if key == 12 {  // ^L
-            self.load_url()
+        match key {
+            12 => self.load_url(),                                                      // Ctrl+L
+            k if k == ('=' as u8) && (glut::get_modifiers() & ACTIVE_CTRL) != 0 => {    // Ctrl++
+                for self.zoom_callback.each |&callback| {
+                    callback(0.1);
+                }
+            }
+            k if k == 31 && (glut::get_modifiers() & ACTIVE_CTRL) != 0 => {             // Ctrl+-
+                for self.zoom_callback.each |&callback| {
+                    callback(-0.1);
+                }
+            }
+            _ => {}
         }
     }
 
     /// Helper function to handle a click
-    fn handle_click(&self, x: c_int, y: c_int) {
-        match self.click_callback {
+    fn handle_mouse(&self, button: c_int, state: c_int, x: c_int, y: c_int) {
+        // FIXME(tkuehn): max pixel dist should be based on pixel density
+        let max_pixel_dist = 10f;
+        match self.mouse_callback {
             None => {}
-            Some(callback) => callback(Point2D(x as f32, y as f32)),
+            Some(callback) => {
+                let event: WindowMouseEvent;
+                match state {
+                    glut::MOUSE_DOWN => {
+                        event = WindowMouseDownEvent(button as uint, Point2D(x as f32, y as f32));
+                        *self.mouse_down_point = Point2D(x, y);
+                        *self.mouse_down_button = button;
+                    }
+                    glut::MOUSE_UP => {
+                        event = WindowMouseUpEvent(button as uint, Point2D(x as f32, y as f32));
+                        if *self.mouse_down_button == button {
+                            let pixel_dist = *self.mouse_down_point - Point2D(x, y);
+                            let pixel_dist = ((pixel_dist.x * pixel_dist.x +
+                                              pixel_dist.y * pixel_dist.y) as float).sqrt();
+                            if pixel_dist < max_pixel_dist {
+                                let click_event = WindowClickEvent(button as uint,
+                                                                   Point2D(x as f32, y as f32));
+                                callback(click_event);
+                            }
+                        }
+                    }
+                    _ => fail!("I cannot recognize the type of mouse action that occured. :-(")
+                };
+                callback(event);
+            }
         }
     }
 
     /// Helper function to handle a scroll.
-    fn handle_scroll(&mut self, delta: f32) {
+    fn handle_scroll(&mut self, delta: Point2D<f32>) {
         match self.scroll_callback {
             None => {}
-            Some(callback) => callback(Point2D(0.0, delta)),
+            Some(callback) => callback(delta),
+        }
+    }
+
+    /// Helper function to handle a zoom.
+    fn handle_zoom(&mut self, magnification: f32) {
+        match self.zoom_callback {
+            None => {}
+            Some(callback) => callback(magnification),
         }
     }
 
diff --git a/src/components/main/servo.rc b/src/components/main/servo.rc
index 50a599a0634..b092d4b30a6 100755
--- a/src/components/main/servo.rc
+++ b/src/components/main/servo.rc
@@ -34,7 +34,8 @@ extern mod core_graphics;
 extern mod core_text;
 
 use compositing::CompositorTask;
-use engine::{Engine, LoadUrlMsg};
+use engine::Engine;
+use script::engine_interface::{ExitMsg, LoadUrlMsg};
 
 use core::comm::SharedChan;
 use gfx::opts;
@@ -121,7 +122,7 @@ fn run(opts: &Opts) {
     // Shut the engine down.
     debug!("master: Shut down");
     let (exit_response_from_engine, exit_chan) = comm::stream();
-    engine_task.send(engine::ExitMsg(exit_chan));
+    engine_task.send(ExitMsg(exit_chan));
     exit_response_from_engine.recv();
 }
 
diff --git a/src/components/main/windowing.rs b/src/components/main/windowing.rs
index 9a9cefaf03b..888851cbbf1 100644
--- a/src/components/main/windowing.rs
+++ b/src/components/main/windowing.rs
@@ -6,6 +6,14 @@
 
 use geom::point::Point2D;
 use geom::size::Size2D;
+use gfx::compositor::RenderState;
+use script::compositor_interface::ReadyState;
+
+pub enum WindowMouseEvent {
+    WindowClickEvent(uint, Point2D<f32>),
+    WindowMouseDownEvent(uint, Point2D<f32>),
+    WindowMouseUpEvent(uint, Point2D<f32>),
+}
 
 /// Type of the function that is called when the screen is to be redisplayed.
 pub type CompositeCallback = @fn();
@@ -16,13 +24,15 @@ pub type ResizeCallback = @fn(uint, uint);
 /// Type of the function that is called when a new URL is to be loaded.
 pub type LoadUrlCallback = @fn(&str);
 
-/// Type of the function that is called when hit testing is to be performed.
-/// FIXME this currently does not discriminate between left and right clicks or any modifiers
-pub type ClickCallback = @fn(Point2D<f32>);
+/// Type of the function that is called when a mouse hit test is to be performed.
+pub type MouseCallback = @fn(WindowMouseEvent);
 
 /// Type of the function that is called when the user scrolls.
 pub type ScrollCallback = @fn(Point2D<f32>);
 
+///Type of the function that is called when the user zooms.
+pub type ZoomCallback = @fn(f32);
+
 /// Methods for an abstract Application.
 pub trait ApplicationMethods {
     fn new() -> Self;
@@ -43,13 +53,19 @@ pub trait WindowMethods<A> {
     /// Registers a callback to run when a new URL is to be loaded.
     pub fn set_load_url_callback(&mut self, new_load_url_callback: LoadUrlCallback);
     /// Registers a callback to run when the user clicks.
-    pub fn set_click_callback(&mut self, new_click_callback: ClickCallback);
+    pub fn set_mouse_callback(&mut self, new_mouse_callback: MouseCallback);
     /// Registers a callback to run when the user scrolls.
     pub fn set_scroll_callback(&mut self, new_scroll_callback: ScrollCallback);
+    /// Registers a callback to run when the user zooms.
+    pub fn set_zoom_callback(&mut self, new_zoom_callback: ZoomCallback);
 
     /// Spins the event loop.
     pub fn check_loop(@mut self);
     /// Schedules a redisplay at the next turn of the event loop.
     pub fn set_needs_display(@mut self);
+    /// Sets the ready state of the current page.
+    pub fn set_ready_state(@mut self, ready_state: ReadyState);
+    /// Sets the render state of the current page.
+    pub fn set_render_state(@mut self, render_state: RenderState);
 }
 
diff --git a/src/components/net/util.rs b/src/components/net/util.rs
index ec1aea92e86..cd8a177a7ef 100644
--- a/src/components/net/util.rs
+++ b/src/components/net/util.rs
@@ -5,11 +5,11 @@
 use core::comm::{Chan, Port};
 
 pub fn spawn_listener<A: Owned>(f: ~fn(Port<A>)) -> Chan<A> {
-    let (setup_po, setup_ch) = comm::stream();
+    let (setup_port, setup_chan) = comm::stream();
     do task::spawn {
-        let (po, ch) = comm::stream();
-        setup_ch.send(ch);
-        f(po);
+        let (port, chan) = comm::stream();
+        setup_chan.send(chan);
+        f(port);
     }
-    setup_po.recv()
+    setup_port.recv()
 }
diff --git a/src/components/script/compositor_interface.rs b/src/components/script/compositor_interface.rs
new file mode 100644
index 00000000000..8e48e9f1492
--- /dev/null
+++ b/src/components/script/compositor_interface.rs
@@ -0,0 +1,19 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! The high-level interface from script to compositor. Using this abstract interface helps reduce
+/// coupling between these two components
+
+pub enum ReadyState {
+    /// Informs the compositor that a page is loading. Used for setting status
+    Loading,
+    /// Informs the compositor that a page is performing layout. Used for setting status
+    PerformingLayout,
+    /// Informs the compositor that a page is finished loading. Used for setting status
+    FinishedLoading,
+}
+
+pub trait CompositorInterface : Clone {
+    fn set_ready_state(&self, ReadyState);
+}
diff --git a/src/components/script/dom/event.rs b/src/components/script/dom/event.rs
index a0ef39d8fca..6c11bcd3411 100644
--- a/src/components/script/dom/event.rs
+++ b/src/components/script/dom/event.rs
@@ -12,7 +12,9 @@ use geom::point::Point2D;
 pub enum Event {
     ResizeEvent(uint, uint, comm::Chan<()>),
     ReflowEvent,
-    ClickEvent(Point2D<f32>),
+    ClickEvent(uint, Point2D<f32>),
+    MouseDownEvent(uint, Point2D<f32>),
+    MouseUpEvent(uint, Point2D<f32>),
 }
 
 pub struct Event_ {
diff --git a/src/components/script/dom/window.rs b/src/components/script/dom/window.rs
index a5904b642c7..aa375a4d614 100644
--- a/src/components/script/dom/window.rs
+++ b/src/components/script/dom/window.rs
@@ -4,6 +4,7 @@
 
 use dom::bindings::utils::WrapperCache;
 use dom::bindings::window;
+
 use layout_interface::ReflowForScriptQuery;
 use script_task::{ExitMsg, FireTimerMsg, ScriptMsg, ScriptContext};
 
diff --git a/src/components/script/engine_interface.rs b/src/components/script/engine_interface.rs
new file mode 100644
index 00000000000..2705ebdb137
--- /dev/null
+++ b/src/components/script/engine_interface.rs
@@ -0,0 +1,17 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! The high-level interface from script to engine. Using this abstract interface helps reduce
+/// coupling between these two components
+
+use core::comm::{Chan, SharedChan};
+use std::net::url::Url;
+
+pub type EngineTask = SharedChan<Msg>;
+
+pub enum Msg {
+    LoadUrlMsg(Url),
+    ExitMsg(Chan<()>),
+}
+
diff --git a/src/components/script/html/cssparse.rs b/src/components/script/html/cssparse.rs
index 9ee789d6e3e..7d1e4214462 100644
--- a/src/components/script/html/cssparse.rs
+++ b/src/components/script/html/cssparse.rs
@@ -43,6 +43,7 @@ pub fn spawn_css_parser(provenance: StylesheetProvenance,
 fn data_stream(provenance: StylesheetProvenance, resource_task: ResourceTask) -> DataStream {
     match provenance {
         UrlProvenance(url) => {
+            debug!("cssparse: loading style sheet at %s", url.to_str());
             let (input_port, input_chan) = comm::stream();
             resource_task.send(Load(url, input_chan));
             resource_port_to_data_stream(input_port)
diff --git a/src/components/script/html/hubbub_html_parser.rs b/src/components/script/html/hubbub_html_parser.rs
index db67b48f035..f604038c58b 100644
--- a/src/components/script/html/hubbub_html_parser.rs
+++ b/src/components/script/html/hubbub_html_parser.rs
@@ -129,11 +129,13 @@ fn js_script_listener(to_parent: Chan<~[~[u8]]>,
                                 buf += data;
                             }
                             Done(Ok(*)) => {
-                                result_chan.send(buf);
+                                result_chan.send(Some(buf));
                                 break;
                             }
                             Done(Err(*)) => {
                                 error!("error loading script %s", url.to_str());
+                                result_chan.send(None);
+                                break;
                             }
                         }
                     }
@@ -146,7 +148,7 @@ fn js_script_listener(to_parent: Chan<~[~[u8]]>,
         }
     }
 
-    let js_scripts = vec::map(result_vec, |result_port| result_port.recv());
+    let js_scripts = vec::filter_map(result_vec, |result_port| result_port.recv());
     to_parent.send(js_scripts);
 }
 
diff --git a/src/components/script/script.rc b/src/components/script/script.rc
index 0c40fc8aab3..2d608e4d25b 100644
--- a/src/components/script/script.rc
+++ b/src/components/script/script.rc
@@ -64,6 +64,8 @@ pub mod html {
     pub mod hubbub_html_parser;
 }
 
+pub mod compositor_interface;
+pub mod engine_interface;
 pub mod layout_interface;
 pub mod script_task;
 
diff --git a/src/components/script/script_task.rs b/src/components/script/script_task.rs
index 66a4e9e4727..69890abb5cb 100644
--- a/src/components/script/script_task.rs
+++ b/src/components/script/script_task.rs
@@ -5,9 +5,11 @@
 /// The script task is the task that owns the DOM in memory, runs JavaScript, and spawns parsing
 /// and layout tasks.
 
+use compositor_interface::{ReadyState, Loading, PerformingLayout, FinishedLoading};
 use dom::bindings::utils::GlobalStaticData;
 use dom::document::Document;
-use dom::event::{Event, ResizeEvent, ReflowEvent, ClickEvent};
+use dom::element::Element;
+use dom::event::{Event, ResizeEvent, ReflowEvent, ClickEvent, MouseDownEvent, MouseUpEvent};
 use dom::node::{AbstractNode, ScriptView, define_bindings};
 use dom::window::Window;
 use layout_interface::{AddStylesheetMsg, DocumentDamage, DocumentDamageLevel, HitTestQuery};
@@ -15,6 +17,7 @@ use layout_interface::{HitTestResponse, LayoutQuery, LayoutResponse, LayoutTask}
 use layout_interface::{MatchSelectorsDocumentDamage, QueryMsg, Reflow, ReflowDocumentDamage};
 use layout_interface::{ReflowForDisplay, ReflowForScriptQuery, ReflowGoal, ReflowMsg};
 use layout_interface;
+use engine_interface::{EngineTask, LoadUrlMsg};
 
 use core::cast::transmute;
 use core::cell::Cell;
@@ -37,6 +40,7 @@ use js;
 use servo_net::image_cache_task::ImageCacheTask;
 use servo_net::resource_task::ResourceTask;
 use servo_util::tree::TreeNodeRef;
+use servo_util::url::make_url;
 use std::net::url::Url;
 use std::net::url;
 
@@ -50,6 +54,8 @@ pub enum ScriptMsg {
     SendEventMsg(Event),
     /// Fires a JavaScript timeout.
     FireTimerMsg(~TimerData),
+    /// Notifies script that reflow is finished.
+    ReflowCompleteMsg,
     /// Exits the engine.
     ExitMsg,
 }
@@ -64,12 +70,15 @@ impl ScriptTask {
     /// Creates a new script task.
     pub fn new(script_port: Port<ScriptMsg>,
                script_chan: SharedChan<ScriptMsg>,
+               engine_task: EngineTask,
+               //FIXME(rust #5192): workaround for lack of working ~Trait
+               compositor_task: ~fn(ReadyState),
                layout_task: LayoutTask,
                resource_task: ResourceTask,
                image_cache_task: ImageCacheTask)
                -> ScriptTask {
         let (script_chan_copy, script_port) = (script_chan.clone(), Cell(script_port));
-
+        let compositor_task = Cell(compositor_task);
         // FIXME: rust#6399
         let mut the_task = task();
         the_task.sched_mode(SingleThreaded);
@@ -77,6 +86,8 @@ impl ScriptTask {
             let script_context = ScriptContext::new(layout_task.clone(),
                                                     script_port.take(),
                                                     script_chan_copy.clone(),
+                                                    engine_task.clone(),
+                                                    compositor_task.take(),
                                                     resource_task.clone(),
                                                     image_cache_task.clone());
             script_context.start();
@@ -116,6 +127,11 @@ pub struct ScriptContext {
     /// messages.
     script_chan: SharedChan<ScriptMsg>,
 
+    /// For communicating load url messages to the engine
+    engine_task: EngineTask,
+    /// For communicating loading messages to the compositor
+    compositor_task: ~fn(ReadyState),
+
     /// The JavaScript runtime.
     js_runtime: js::rust::rt,
     /// The JavaScript context.
@@ -167,6 +183,8 @@ impl ScriptContext {
     pub fn new(layout_task: LayoutTask,
                script_port: Port<ScriptMsg>,
                script_chan: SharedChan<ScriptMsg>,
+               engine_task: EngineTask,
+               compositor_task: ~fn(ReadyState),
                resource_task: ResourceTask,
                img_cache_task: ImageCacheTask)
                -> @mut ScriptContext {
@@ -190,6 +208,9 @@ impl ScriptContext {
             script_port: script_port,
             script_chan: script_chan,
 
+            engine_task: engine_task,
+            compositor_task: compositor_task,
+
             js_runtime: js_runtime,
             js_context: js_context,
             js_compartment: compartment,
@@ -243,6 +264,10 @@ impl ScriptContext {
                 self.handle_fire_timer_msg(timer_data);
                 true
             }
+            ReflowCompleteMsg => {
+                self.handle_reflow_complete_msg();
+                true
+            }
             ExitMsg => {
                 self.handle_exit_msg();
                 false
@@ -287,6 +312,12 @@ impl ScriptContext {
         self.reflow(ReflowForScriptQuery)
     }
 
+    /// Handles a notification that reflow completed.
+    fn handle_reflow_complete_msg(&mut self) {
+        self.layout_join_port = None;
+        self.set_ready_state(FinishedLoading)
+    }
+
     /// Handles a request to exit the script task and shut down layout.
     fn handle_exit_msg(&mut self) {
         self.join_layout();
@@ -297,6 +328,12 @@ impl ScriptContext {
         self.layout_task.chan.send(layout_interface::ExitMsg)
     }
 
+    // tells the compositor when loading starts and finishes
+    // FIXME ~compositor_interface doesn't work right now, which is why this is necessary
+    fn set_ready_state(&self, msg: ReadyState) {
+        (self.compositor_task)(msg);
+    }
+
     /// The entry point to document loading. Defines bindings, sets up the window and document
     /// objects, parses HTML and CSS, and kicks off initial layout.
     fn load(&mut self, url: Url) {
@@ -308,6 +345,7 @@ impl ScriptContext {
             self.bindings_initialized = true
         }
 
+        self.set_ready_state(Loading);
         // Parse HTML.
         //
         // Note: We can parse the next document in parallel with any previous documents.
@@ -398,6 +436,9 @@ impl ScriptContext {
         // Now, join the layout so that they will see the latest changes we have made.
         self.join_layout();
 
+        // Tell the user that we're performing layout.
+        self.set_ready_state(PerformingLayout);
+
         // Layout will let us know when it's done.
         let (join_port, join_chan) = comm::stream();
         self.layout_join_port = Some(join_port);
@@ -410,8 +451,8 @@ impl ScriptContext {
                     document_root: root_frame.document.root,
                     url: copy root_frame.url,
                     goal: goal,
-                    script_chan: self.script_chan.clone(),
                     window_size: self.window_size,
+                    script_chan: self.script_chan.clone(),
                     script_join_chan: join_chan,
                     damage: replace(&mut self.damage, None).unwrap(),
                 };
@@ -503,7 +544,7 @@ impl ScriptContext {
                 }
             }
 
-            ClickEvent(point) => {
+            ClickEvent(button, point) => {
                 debug!("ClickEvent: clicked at %?", point);
                 let root = match self.root_frame {
                     Some(ref frame) => frame.document.root,
@@ -511,14 +552,51 @@ impl ScriptContext {
                 };
                 match self.query_layout(HitTestQuery(root, point)) {
                     Ok(node) => match node {
-                        HitTestResponse(node) => debug!("clicked on %?", node.debug_str()),
+                        HitTestResponse(node) => {
+                            debug!("clicked on %?", node.debug_str());
+                            let mut node = node;
+                            // traverse node generations until a node that is an element is found
+                            while !node.is_element() {
+                                match node.parent_node() {
+                                    Some(parent) => {
+                                        node = parent;
+                                    }
+                                    None => break
+                                }
+                            }
+                            if node.is_element() {
+                                do node.with_imm_element |element| {
+                                    match element.tag_name {
+                                        ~"a" => self.load_url_from_element(element),
+                                        _ => {}
+                                    }
+                                }
+                            }
+                        }
                         _ => fail!(~"unexpected layout reply")
                     },
                     Err(()) => {
-                        println(fmt!("layout query error"));
+                        debug!(fmt!("layout query error"));
                     }
                 };
             }
+            MouseDownEvent(*) => {}
+            MouseUpEvent(*) => {}
+        }
+    }
+
+    priv fn load_url_from_element(&self, element: &Element) {
+        // if the node's element is "a," load url from href attr
+        for element.attrs.each |attr| {
+            if attr.name == ~"href" {
+                debug!("clicked on link to %?", attr.value); 
+                let current_url = match self.root_frame {
+                    Some(ref frame) => Some(frame.url.clone()),
+                    None => None
+                };
+                let url = make_url(attr.value.clone(), current_url);
+                self.engine_task.send(LoadUrlMsg(url));
+            }
         }
     }
 }
diff --git a/src/components/util/time.rs b/src/components/util/time.rs
index 8bb698981f0..4ea5828e892 100644
--- a/src/components/util/time.rs
+++ b/src/components/util/time.rs
@@ -6,62 +6,133 @@
 use std::time::precise_time_ns;
 use core::cell::Cell;
 use core::comm::{Port, SharedChan};
-use core::os::getenv;
+use std::sort::tim_sort;
 
+pub type ProfilerChan = SharedChan<ProfilerMsg>;
+pub type ProfilerPort = Port<ProfilerMsg>;
+
+#[deriving(Eq)]
 pub enum ProfilerCategory {
     CompositingCategory,
-    LayoutPerformCategory,
     LayoutQueryCategory,
+    LayoutPerformCategory,
     LayoutAuxInitCategory,
     LayoutSelectorMatchCategory,
     LayoutTreeBuilderCategory,
     LayoutMainCategory,
+    LayoutShapingCategory,
     LayoutDispListBuildCategory,
     GfxRegenAvailableFontsCategory,
     RenderingPrepBuffCategory,
     RenderingWaitSubtasksCategory,
     RenderingCategory,
+    // hackish but helps prevent errors when adding new categories
+    NUM_BUCKETS,
 }
-// change this whenever buckets are added/rm'd
-static NUM_BUCKETS: uint = 12;
+// FIXME(#5873) this should be initialized by a NUM_BUCKETS cast,
+static BUCKETS: uint = 13;
 
-pub type ProfilerChan = SharedChan<(ProfilerCategory, uint)>;
-pub type ProfilerPort = Port<(ProfilerCategory, uint)>;
+pub enum ProfilerMsg {
+    // Normal message used for reporting time
+    TimeMsg(ProfilerCategory, f64),
+    // Message used to force print the profiling metrics
+    ForcePrintMsg,
+}
+
+// front-end representation of the profiler used to communicate with the profiler context
 pub struct ProfilerTask {
     chan: ProfilerChan,
 }
 
+// back end of the profiler that handles data aggregation and performance metrics
+pub struct ProfilerContext {
+    port: ProfilerPort,
+    buckets: ~[(ProfilerCategory, ~[f64])],
+    verbose: bool,
+    period: f64,
+    last_print: f64,
+}
+
+impl ProfilerCategory {
+
+    // convenience function to not have to cast every time
+    pub fn num_buckets() -> uint {
+        NUM_BUCKETS as uint
+    }
+
+    // enumeration of all ProfilerCategory types
+    // FIXME(tkuehn): this is ugly and error-prone,
+    // but currently we lack better alternatives without an enum enumeration
+    priv fn empty_buckets() -> ~[(ProfilerCategory, ~[f64])] {
+        let mut vec = ~[];
+        vec.push((CompositingCategory, ~[]));
+        vec.push((LayoutQueryCategory, ~[]));
+        vec.push((LayoutPerformCategory, ~[]));
+        vec.push((LayoutAuxInitCategory, ~[]));
+        vec.push((LayoutSelectorMatchCategory, ~[]));
+        vec.push((LayoutTreeBuilderCategory, ~[]));
+        vec.push((LayoutMainCategory, ~[]));
+        vec.push((LayoutShapingCategory, ~[]));
+        vec.push((LayoutDispListBuildCategory, ~[]));
+        vec.push((GfxRegenAvailableFontsCategory, ~[]));
+        vec.push((RenderingPrepBuffCategory, ~[]));
+        vec.push((RenderingWaitSubtasksCategory, ~[]));
+        vec.push((RenderingCategory, ~[]));
+
+        ProfilerCategory::check_order(vec);
+        vec
+    }
+
+    priv fn check_order(vec: &[(ProfilerCategory, ~[f64])]) {
+        for vec.each |&(category, _)| {
+            if category != vec[category as uint].first() {
+                fail!("Enum category does not match bucket index. This is a bug.");
+            }
+        }
+    }
+
+    // some categories are subcategories of LayoutPerformCategory
+    // and should be printed to indicate this
+    pub fn format(self) -> ~str {
+        let padding = match self {
+            LayoutAuxInitCategory | LayoutSelectorMatchCategory | LayoutTreeBuilderCategory |
+            LayoutMainCategory | LayoutDispListBuildCategory | LayoutShapingCategory=> " - ",
+            _ => ""
+        };
+        fmt!("%s%?", padding, self)
+    }
+}
+
 impl ProfilerTask {
-    pub fn new(prof_port: ProfilerPort,
-               prof_chan: ProfilerChan)
+    pub fn new(profiler_port: ProfilerPort,
+               profiler_chan: ProfilerChan,
+               period: Option<f64>)
                -> ProfilerTask {
-        let prof_port = Cell(prof_port);
+        let profiler_port = Cell(profiler_port);
 
         do spawn {
-            let mut profiler_context = ProfilerContext::new(prof_port.take());
+            let mut profiler_context = ProfilerContext::new(profiler_port.take(), period);
             profiler_context.start();
         }
 
         ProfilerTask {
-            chan: prof_chan
+            chan: profiler_chan
         }
     }
 }
 
-pub struct ProfilerContext {
-    port: ProfilerPort,
-    buckets: [~[uint], ..NUM_BUCKETS],
-    verbose: Option<~str>,
-    mut last_print: u64,
-}
-
 impl ProfilerContext {
-    pub fn new(port: ProfilerPort) -> ProfilerContext {
+    pub fn new(port: ProfilerPort, period: Option<f64>) -> ProfilerContext {
+        let (verbose, period) = match period {
+            Some(period) => (true, period),
+            None => (false, 0f64)
+        };
         ProfilerContext {
             port: port,
-            buckets: [~[], ..NUM_BUCKETS],
-            verbose: getenv("SERVO_PROFILER"),
-            last_print: 0,
+            buckets: ProfilerCategory::empty_buckets(),
+            verbose: verbose,
+            period: period,
+            last_print: 0f64,
         }
     }
 
@@ -72,52 +143,64 @@ impl ProfilerContext {
         }
     }
 
-    priv fn handle_msg(&mut self, msg: (ProfilerCategory, uint)) {
-        let (prof_msg, t) = msg;
-        self.buckets[prof_msg as uint].push(t);
-        if self.verbose.is_some() {
-            let cur_time = precise_time_ns() / 1000000000u64;
-            if cur_time - self.last_print > 5 {
-                self.last_print = cur_time;
-                let mut i = 0;
-                for self.buckets.each |bucket| {
-                    let prof_msg = match i {
-                        // must be in same order as ProfilerCategory
-                        0 => CompositingCategory,
-                        1 => LayoutPerformCategory,
-                        2 => LayoutQueryCategory,
-                        3 => LayoutAuxInitCategory,
-                        4 => LayoutSelectorMatchCategory,
-                        5 => LayoutTreeBuilderCategory,
-                        6 => LayoutMainCategory,
-                        7 => LayoutDispListBuildCategory,
-                        8 => GfxRegenAvailableFontsCategory,
-                        9 => RenderingPrepBuffCategory,
-                        10 => RenderingWaitSubtasksCategory,
-                        11 => RenderingCategory,
-                        _ => fail!()
-                    };
-                    io::println(fmt!("%?: %f", prof_msg,
-                                 (bucket.foldl(0 as uint, |a, b| a + *b) as float) / 
-                                 (bucket.len() as float)));
-                    i += 1;
+    priv fn handle_msg(&mut self, msg: ProfilerMsg) {
+        match msg {
+            TimeMsg(category, t) => {
+                // FIXME(#3874): this should be a let (cat, ref mut bucket) = ...,
+                // not a match
+                match self.buckets[category as uint] {
+                    (_, ref mut data) => {
+                        data.push(t);
+                    }
+                }
+
+                if self.verbose {
+                    let cur_time = precise_time_ns() as f64 / 1000000000f64;
+                    if cur_time - self.last_print > self.period {
+                        self.last_print = cur_time;
+                        self.print_buckets();
+                    }
+                }
+            }
+            ForcePrintMsg => self.print_buckets(),
+        };
+    }
+
+    priv fn print_buckets(&mut self) {
+        println(fmt!("%31s %15s %15s %15s %15s %15s",
+                         "_category (ms)_", "_mean (ms)_", "_median (ms)_",
+                         "_min (ms)_", "_max (ms)_", "_bucket size_"));
+        for vec::each_mut(self.buckets) |bucket| {
+            match *bucket {
+                (category, ref mut data) => {
+                    tim_sort(*data);
+                    let data_len = data.len();
+                    if data_len > 0 {
+                        let (mean, median, min, max) =
+                            (data.foldl(0f64, |a, b| a + *b) / (data_len as f64),
+                             data[data_len / 2],
+                             data.min(),
+                             data.max());
+                        println(fmt!("%-30s: %15.4? %15.4? %15.4? %15.4? %15u",
+                                     category.format(), mean, median, min, max, data_len));
+                    }
                 }
-                io::println("");
             }
         }
-
+        println("");
     }
 }
 
-pub fn profile<T>(cat: ProfilerCategory, 
-                  prof_chan: ProfilerChan,
+
+pub fn profile<T>(category: ProfilerCategory, 
+                  profiler_chan: ProfilerChan,
                   callback: &fn() -> T)
                   -> T {
     let start_time = precise_time_ns();
     let val = callback();
     let end_time = precise_time_ns();
-    let ms = ((end_time - start_time) / 1000000u64) as uint;
-    prof_chan.send((cat, ms));
+    let ms = ((end_time - start_time) as f64 / 1000000f64);
+    profiler_chan.send(TimeMsg(category, ms));
     return val;
 }
 
@@ -125,9 +208,9 @@ pub fn time<T>(msg: &str, callback: &fn() -> T) -> T{
     let start_time = precise_time_ns();
     let val = callback();
     let end_time = precise_time_ns();
-    let ms = ((end_time - start_time) / 1000000u64) as uint;
-    if ms >= 5 {
-        debug!("%s took %u ms", msg, ms);
+    let ms = ((end_time - start_time) as f64 / 1000000f64);
+    if ms >= 5f64 {
+        debug!("%s took %? ms", msg, ms);
     }
     return val;
 }
diff --git a/src/components/util/url.rs b/src/components/util/url.rs
index fea0df23b73..0d2b86f75a2 100644
--- a/src/components/util/url.rs
+++ b/src/components/util/url.rs
@@ -30,8 +30,13 @@ pub fn make_url(str_url: ~str, current_url: Option<Url>) -> Url {
         } else {
             let current_url = current_url.get();
             debug!("make_url: current_url: %?", current_url);
-            if current_url.path.is_empty() || current_url.path.ends_with("/") {
-                current_url.scheme + "://" + current_url.host + "/" + str_url
+            if str_url.starts_with("//") {
+                current_url.scheme + ":" + str_url
+            } else if current_url.path.is_empty() ||
+                      str_url.starts_with("/") {
+                current_url.scheme + "://" +
+                current_url.host + "/" +
+                str_url.trim_left_chars([ '/' ])
             } else {
                 let mut path = ~[];
                 for str::each_split_char(current_url.path, '/') |p| {
diff --git a/src/support/geom/rust-geom b/src/support/geom/rust-geom
index ebf1cc8f2e8..efba52c0209 160000
--- a/src/support/geom/rust-geom
+++ b/src/support/geom/rust-geom
@@ -1 +1 @@
-Subproject commit ebf1cc8f2e8a39f31da2575981fad966aa7da904
+Subproject commit efba52c020945e08f00bebf8ff54ec292e95eced
diff --git a/src/support/layers/rust-layers b/src/support/layers/rust-layers
index af960707afc..f4ec5a4590a 160000
--- a/src/support/layers/rust-layers
+++ b/src/support/layers/rust-layers
@@ -1 +1 @@
-Subproject commit af960707afc666ac38591f1f0545f18a1bb89471
+Subproject commit f4ec5a4590a39804ef38faaab4b6749e5c7eb4c6
diff --git a/src/test/html/box-model-smoketest.html b/src/test/html/box-model-smoketest.html
new file mode 100644
index 00000000000..d297b63e018
--- /dev/null
+++ b/src/test/html/box-model-smoketest.html
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<html>
+<head>
+<title>box model smoketest</title>
+<style>
+body {
+    margin: 0;
+}
+#outer {
+    background-color: red;
+    margin: 0;
+    padding: 0;
+}
+#inner {
+    margin: 16px;
+    border: solid green 16px;
+    padding: 16px;
+    background-color: blue;
+    color: white;
+}
+</style>
+</head>
+<body><div id=outer><div id=inner>Ten points for Gryffindor</div></div></body>
+</html>
+
diff --git a/src/test/html/test_slam_layout.js b/src/test/html/test_slam_layout.js
index 5d1726b904e..7149fba8044 100644
--- a/src/test/html/test_slam_layout.js
+++ b/src/test/html/test_slam_layout.js
@@ -12,3 +12,4 @@ for (var i = 0; i < count; i++) {
 }
 var stop = new Date();
 window.alert((stop - start) / count * 1e6 + " ns/layout");
+window.close();