diff --git a/Cargo.lock b/Cargo.lock
index c72223c0385..1e4e2bd7e6c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -182,6 +182,7 @@ dependencies = [
  "bluetooth_traits 0.0.1",
  "compositing 0.0.1",
  "device 0.0.1 (git+https://github.com/servo/devices)",
+ "embedder_traits 0.0.1",
  "ipc-channel 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "servo_config 0.0.1",
@@ -419,6 +420,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "compositing"
 version = "0.0.1"
 dependencies = [
+ "embedder_traits 0.0.1",
  "euclid 0.17.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "gfx_traits 0.0.1",
  "gleam 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -770,7 +772,14 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 name = "embedder_traits"
 version = "0.0.1"
 dependencies = [
+ "ipc-channel 0.10.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "log 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "msg 0.0.1",
+ "serde 1.0.37 (registry+https://github.com/rust-lang/crates.io-index)",
+ "servo_url 0.0.1",
+ "style_traits 0.0.1",
+ "webrender_api 0.57.2 (git+https://github.com/servo/webrender)",
 ]
 
 [[package]]
@@ -1850,7 +1859,6 @@ version = "0.0.1"
 dependencies = [
  "base64 0.6.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "brotli 1.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
- "compositing 0.0.1",
  "cookie 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "devtools_traits 0.0.1",
  "embedder_traits 0.0.1",
@@ -2601,6 +2609,7 @@ dependencies = [
  "canvas_traits 0.0.1",
  "cookie 0.10.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "devtools_traits 0.0.1",
+ "embedder_traits 0.0.1",
  "euclid 0.17.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "gfx_traits 0.0.1",
  "hyper 0.10.13 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/components/bluetooth/Cargo.toml b/components/bluetooth/Cargo.toml
index bc172342977..114772a7f99 100644
--- a/components/bluetooth/Cargo.toml
+++ b/components/bluetooth/Cargo.toml
@@ -14,8 +14,12 @@ bitflags = "1.0"
 bluetooth_traits = {path = "../bluetooth_traits"}
 compositing = {path = "../compositing"}
 device = {git = "https://github.com/servo/devices", features = ["bluetooth-test"]}
+embedder_traits = {path = "../embedder_traits"}
 ipc-channel = "0.10"
 log = "0.4"
 servo_config = {path = "../config"}
 servo_rand = {path = "../rand"}
 uuid = {version = "0.6", features = ["v4"]}
+
+[dev-dependencies]
+embedder_traits = { path = "../embedder_traits", features = ["tests"]}
diff --git a/components/bluetooth/lib.rs b/components/bluetooth/lib.rs
index 3df295b56e9..5da42bddc65 100644
--- a/components/bluetooth/lib.rs
+++ b/components/bluetooth/lib.rs
@@ -5,8 +5,8 @@
 #[macro_use]
 extern crate bitflags;
 extern crate bluetooth_traits;
-extern crate compositing;
 extern crate device;
+extern crate embedder_traits;
 extern crate ipc_channel;
 #[macro_use]
 extern crate log;
@@ -21,9 +21,9 @@ use bluetooth_traits::{BluetoothDeviceMsg, BluetoothRequest, BluetoothResponse,
 use bluetooth_traits::{BluetoothError, BluetoothResponseResult, BluetoothResult};
 use bluetooth_traits::blocklist::{uuid_is_blocklisted, Blocklist};
 use bluetooth_traits::scanfilter::{BluetoothScanfilter, BluetoothScanfilterSequence, RequestDeviceoptions};
-use compositing::compositor_thread::{EmbedderMsg, EmbedderProxy};
 use device::bluetooth::{BluetoothAdapter, BluetoothDevice, BluetoothGATTCharacteristic};
 use device::bluetooth::{BluetoothGATTDescriptor, BluetoothGATTService};
+use embedder_traits::{EmbedderMsg, EmbedderProxy};
 use ipc_channel::ipc::{self, IpcReceiver, IpcSender};
 use servo_config::opts;
 use servo_config::prefs::PREFS;
diff --git a/components/compositing/Cargo.toml b/components/compositing/Cargo.toml
index 7715effd551..7dbd1e28688 100644
--- a/components/compositing/Cargo.toml
+++ b/components/compositing/Cargo.toml
@@ -14,6 +14,7 @@ path = "lib.rs"
 default = []
 
 [dependencies]
+embedder_traits = {path = "../embedder_traits"}
 euclid = "0.17"
 gfx_traits = {path = "../gfx_traits"}
 gleam = {version = "0.5", optional = true}
@@ -36,3 +37,6 @@ webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}
 
 [build-dependencies]
 toml = "0.4.5"
+
+[dev-dependencies]
+embedder_traits = { path = "../embedder_traits", features = ["tests"]}
diff --git a/components/compositing/compositor_thread.rs b/components/compositing/compositor_thread.rs
index 2e8dc7a66d6..76b3172b5dd 100644
--- a/components/compositing/compositor_thread.rs
+++ b/components/compositing/compositor_thread.rs
@@ -6,68 +6,21 @@
 
 use SendableFrameTree;
 use compositor::CompositingReason;
+use embedder_traits::EventLoopWaker;
 use gfx_traits::Epoch;
 use ipc_channel::ipc::IpcSender;
-use msg::constellation_msg::{InputMethodType, Key, KeyModifiers, KeyState, PipelineId, TopLevelBrowsingContextId};
-use net_traits::filemanager_thread::FilterPattern;
+use msg::constellation_msg::{PipelineId, TopLevelBrowsingContextId};
 use net_traits::image::base::Image;
 use profile_traits::mem;
 use profile_traits::time;
-use script_traits::{AnimationState, ConstellationMsg, EventResult, LoadData};
-use servo_url::ServoUrl;
+use script_traits::{AnimationState, ConstellationMsg, EventResult};
 use std::fmt::{Debug, Error, Formatter};
 use std::sync::mpsc::{Receiver, Sender};
-use style_traits::cursor::CursorKind;
 use style_traits::viewport::ViewportConstraints;
 use webrender;
 use webrender_api::{self, DeviceIntPoint, DeviceUintSize};
 
 
-/// Used to wake up the event loop, provided by the servo port/embedder.
-pub trait EventLoopWaker : 'static + Send {
-    fn clone(&self) -> Box<EventLoopWaker + Send>;
-    fn wake(&self);
-}
-
-/// Sends messages to the embedder.
-pub struct EmbedderProxy {
-    pub sender: Sender<EmbedderMsg>,
-    pub event_loop_waker: Box<EventLoopWaker>,
-}
-
-impl EmbedderProxy {
-    pub fn send(&self, msg: EmbedderMsg) {
-        // Send a message and kick the OS event loop awake.
-        if let Err(err) = self.sender.send(msg) {
-            warn!("Failed to send response ({}).", err);
-        }
-        self.event_loop_waker.wake();
-    }
-}
-
-impl Clone for EmbedderProxy {
-    fn clone(&self) -> EmbedderProxy {
-        EmbedderProxy {
-            sender: self.sender.clone(),
-            event_loop_waker: self.event_loop_waker.clone(),
-        }
-    }
-}
-
-/// The port that the embedder receives messages on.
-pub struct EmbedderReceiver {
-    pub receiver: Receiver<EmbedderMsg>
-}
-
-impl EmbedderReceiver {
-    pub fn try_recv_embedder_msg(&mut self) -> Option<EmbedderMsg> {
-        self.receiver.try_recv().ok()
-    }
-    pub fn recv_embedder_msg(&mut self) -> EmbedderMsg {
-        self.receiver.recv().unwrap()
-    }
-}
-
 /// Sends messages to the compositor.
 pub struct CompositorProxy {
     pub sender: Sender<Msg>,
@@ -113,47 +66,6 @@ impl CompositorProxy {
     }
 }
 
-pub enum EmbedderMsg {
-    /// A status message to be displayed by the browser chrome.
-    Status(TopLevelBrowsingContextId, Option<String>),
-    /// Alerts the embedder that the current page has changed its title.
-    ChangePageTitle(TopLevelBrowsingContextId, Option<String>),
-    /// Move the window to a point
-    MoveTo(TopLevelBrowsingContextId, DeviceIntPoint),
-    /// Resize the window to size
-    ResizeTo(TopLevelBrowsingContextId, DeviceUintSize),
-    /// Wether or not to follow a link
-    AllowNavigation(TopLevelBrowsingContextId, ServoUrl, IpcSender<bool>),
-    /// Sends an unconsumed key event back to the embedder.
-    KeyEvent(Option<TopLevelBrowsingContextId>, Option<char>, Key, KeyState, KeyModifiers),
-    /// Changes the cursor.
-    SetCursor(CursorKind),
-    /// A favicon was detected
-    NewFavicon(TopLevelBrowsingContextId, ServoUrl),
-    /// <head> tag finished parsing
-    HeadParsed(TopLevelBrowsingContextId),
-    /// The history state has changed.
-    HistoryChanged(TopLevelBrowsingContextId, Vec<LoadData>, usize),
-    /// Enter or exit fullscreen
-    SetFullscreenState(TopLevelBrowsingContextId, bool),
-    /// The load of a page has begun
-    LoadStart(TopLevelBrowsingContextId),
-    /// The load of a page has completed
-    LoadComplete(TopLevelBrowsingContextId),
-    /// A pipeline panicked. First string is the reason, second one is the backtrace.
-    Panic(TopLevelBrowsingContextId, String, Option<String>),
-    /// Open dialog to select bluetooth device.
-    GetSelectedBluetoothDevice(Vec<String>, IpcSender<Option<String>>),
-    /// Open file dialog to select files. Set boolean flag to true allows to select multiple files.
-    SelectFiles(Vec<FilterPattern>, bool, IpcSender<Option<Vec<String>>>),
-    /// Request to present an IME to the user when an editable element is focused.
-    ShowIME(TopLevelBrowsingContextId, InputMethodType),
-    /// Request to hide the IME when the editable element is blurred.
-    HideIME(TopLevelBrowsingContextId),
-    /// Servo has shut down
-    Shutdown,
-}
-
 /// Messages from the painting thread and the constellation thread to the compositor thread.
 pub enum Msg {
     /// Requests that the compositor shut down.
@@ -233,32 +145,6 @@ impl Debug for Msg {
     }
 }
 
-impl Debug for EmbedderMsg {
-    fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
-        match *self {
-            EmbedderMsg::Status(..) => write!(f, "Status"),
-            EmbedderMsg::ChangePageTitle(..) => write!(f, "ChangePageTitle"),
-            EmbedderMsg::MoveTo(..) => write!(f, "MoveTo"),
-            EmbedderMsg::ResizeTo(..) => write!(f, "ResizeTo"),
-            EmbedderMsg::AllowNavigation(..) => write!(f, "AllowNavigation"),
-            EmbedderMsg::KeyEvent(..) => write!(f, "KeyEvent"),
-            EmbedderMsg::SetCursor(..) => write!(f, "SetCursor"),
-            EmbedderMsg::NewFavicon(..) => write!(f, "NewFavicon"),
-            EmbedderMsg::HeadParsed(..) => write!(f, "HeadParsed"),
-            EmbedderMsg::HistoryChanged(..) => write!(f, "HistoryChanged"),
-            EmbedderMsg::SetFullscreenState(..) => write!(f, "SetFullscreenState"),
-            EmbedderMsg::LoadStart(..) => write!(f, "LoadStart"),
-            EmbedderMsg::LoadComplete(..) => write!(f, "LoadComplete"),
-            EmbedderMsg::Panic(..) => write!(f, "Panic"),
-            EmbedderMsg::GetSelectedBluetoothDevice(..) => write!(f, "GetSelectedBluetoothDevice"),
-            EmbedderMsg::SelectFiles(..) => write!(f, "SelectFiles"),
-            EmbedderMsg::ShowIME(..) => write!(f, "ShowIME"),
-            EmbedderMsg::HideIME(..) => write!(f, "HideIME"),
-            EmbedderMsg::Shutdown => write!(f, "Shutdown"),
-        }
-    }
-}
-
 /// Data used to construct a compositor.
 pub struct InitialCompositorState {
     /// A channel to the compositor.
diff --git a/components/compositing/lib.rs b/components/compositing/lib.rs
index f19230ebcdd..59c7600fcfd 100644
--- a/components/compositing/lib.rs
+++ b/components/compositing/lib.rs
@@ -4,6 +4,7 @@
 
 #![deny(unsafe_code)]
 
+extern crate embedder_traits;
 extern crate euclid;
 extern crate gfx_traits;
 #[cfg(feature = "gleam")]
diff --git a/components/compositing/windowing.rs b/components/compositing/windowing.rs
index 11143e5eaa9..b81b1e3ebc7 100644
--- a/components/compositing/windowing.rs
+++ b/components/compositing/windowing.rs
@@ -4,7 +4,7 @@
 
 //! Abstract windowing methods. The concrete implementations of these can be found in `platform/`.
 
-use compositor_thread::EventLoopWaker;
+use embedder_traits::EventLoopWaker;
 use euclid::TypedScale;
 #[cfg(feature = "gleam")]
 use gleam::gl;
@@ -78,6 +78,8 @@ pub enum WindowEvent {
     NewBrowser(ServoUrl, IpcSender<TopLevelBrowsingContextId>),
     /// Close a top level browsing context
     CloseBrowser(TopLevelBrowsingContextId),
+    /// Panic a top level browsing context.
+    SendError(Option<TopLevelBrowsingContextId>, String),
     /// Make a top level browsing context visible, hiding the previous
     /// visible one.
     SelectBrowser(TopLevelBrowsingContextId),
@@ -106,6 +108,7 @@ impl Debug for WindowEvent {
             WindowEvent::Quit => write!(f, "Quit"),
             WindowEvent::Reload(..) => write!(f, "Reload"),
             WindowEvent::NewBrowser(..) => write!(f, "NewBrowser"),
+            WindowEvent::SendError(..) => write!(f, "SendError"),
             WindowEvent::CloseBrowser(..) => write!(f, "CloseBrowser"),
             WindowEvent::SelectBrowser(..) => write!(f, "SelectBrowser"),
             WindowEvent::ToggleWebRenderDebug(..) => write!(f, "ToggleWebRenderDebug"),
diff --git a/components/constellation/constellation.rs b/components/constellation/constellation.rs
index 970073cafbf..4f5e0612f44 100644
--- a/components/constellation/constellation.rs
+++ b/components/constellation/constellation.rs
@@ -98,10 +98,11 @@ use canvas_traits::canvas::CanvasId;
 use canvas_traits::canvas::CanvasMsg;
 use clipboard::{ClipboardContext, ClipboardProvider};
 use compositing::SendableFrameTree;
-use compositing::compositor_thread::{CompositorProxy, EmbedderMsg, EmbedderProxy};
+use compositing::compositor_thread::CompositorProxy;
 use compositing::compositor_thread::Msg as ToCompositorMsg;
 use debugger;
 use devtools_traits::{ChromeToDevtoolsControlMsg, DevtoolsControlMsg};
+use embedder_traits::{EmbedderMsg, EmbedderProxy};
 use euclid::{Size2D, TypedSize2D, TypedScale};
 use event_loop::EventLoop;
 use gfx::font_cache_thread::FontCacheThread;
@@ -969,6 +970,15 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             FromCompositorMsg::CloseBrowser(top_level_browsing_context_id) => {
                 self.handle_close_top_level_browsing_context(top_level_browsing_context_id);
             }
+            // Panic a top level browsing context.
+            FromCompositorMsg::SendError(top_level_browsing_context_id, error) => {
+                debug!("constellation got SendError message");
+                if let Some(id) = top_level_browsing_context_id {
+                    self.handle_panic(id, error, None);
+                } else {
+                    warn!("constellation got a SendError message without top level id");
+                }
+            }
             // Send frame tree to WebRender. Make it visible.
             FromCompositorMsg::SelectBrowser(top_level_browsing_context_id) => {
                 self.send_frame_tree(top_level_browsing_context_id);
@@ -1014,12 +1024,10 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                 Some(ctx) => ctx,
         };
 
-        let source_is_top_level_pipeline = self.browsing_contexts
-            .get(&BrowsingContextId::from(source_top_ctx_id))
-            .map(|ctx| ctx.pipeline_id == source_pipeline_id)
-            .unwrap_or(false);
-
         match content {
+            FromScriptMsg::ForwardToEmbedder(embedder_msg) => {
+                self.embedder_proxy.send(embedder_msg);
+            }
             FromScriptMsg::PipelineExited => {
                 self.handle_pipeline_exited(source_pipeline_id);
             }
@@ -1119,34 +1127,12 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                     warn!("Error replying to remove iframe ({})", e);
                 }
             }
-            FromScriptMsg::NewFavicon(url) => {
-                if source_is_top_level_pipeline {
-                    self.embedder_proxy.send(EmbedderMsg::NewFavicon(source_top_ctx_id, url));
-                }
-            }
-            FromScriptMsg::HeadParsed => {
-                if source_is_top_level_pipeline {
-                    self.embedder_proxy.send(EmbedderMsg::HeadParsed(source_top_ctx_id));
-                }
-            }
             FromScriptMsg::CreateCanvasPaintThread(size, sender) => {
                 self.handle_create_canvas_paint_thread_msg(&size, sender)
             }
-            FromScriptMsg::NodeStatus(message) => {
-                self.embedder_proxy.send(EmbedderMsg::Status(source_top_ctx_id, message));
-            }
             FromScriptMsg::SetDocumentState(state) => {
                 self.document_states.insert(source_pipeline_id, state);
             }
-            FromScriptMsg::Alert(message, sender) => {
-                self.handle_alert(source_top_ctx_id, message, sender);
-            }
-            FromScriptMsg::MoveTo(point) => {
-                self.embedder_proxy.send(EmbedderMsg::MoveTo(source_top_ctx_id, point));
-            }
-            FromScriptMsg::ResizeTo(size) => {
-                self.embedder_proxy.send(EmbedderMsg::ResizeTo(source_top_ctx_id, size));
-            }
             FromScriptMsg::GetClientWindow(send) => {
                 self.compositor_proxy.send(ToCompositorMsg::GetClientWindow(send));
             }
@@ -1162,15 +1148,6 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             FromScriptMsg::LogEntry(thread_name, entry) => {
                 self.handle_log_entry(Some(source_top_ctx_id), thread_name, entry);
             }
-            FromScriptMsg::SetTitle(title) => {
-                if source_is_top_level_pipeline {
-                    self.embedder_proxy.send(EmbedderMsg::ChangePageTitle(source_top_ctx_id, title))
-                }
-            }
-            FromScriptMsg::SendKeyEvent(ch, key, key_state, key_modifiers) => {
-                let event = EmbedderMsg::KeyEvent(Some(source_top_ctx_id), ch, key, key_state, key_modifiers);
-                self.embedder_proxy.send(event);
-            }
             FromScriptMsg::TouchEventProcessed(result) => {
                 self.compositor_proxy.send(ToCompositorMsg::TouchEventProcessed(result))
             }
@@ -1208,15 +1185,6 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
             FromScriptMsg::BroadcastStorageEvent(storage, url, key, old_value, new_value) => {
                 self.handle_broadcast_storage_event(source_pipeline_id, storage, url, key, old_value, new_value);
             }
-            FromScriptMsg::SetFullscreenState(state) => {
-                self.embedder_proxy.send(EmbedderMsg::SetFullscreenState(source_top_ctx_id, state));
-            }
-            FromScriptMsg::ShowIME(kind) => {
-                self.embedder_proxy.send(EmbedderMsg::ShowIME(source_top_ctx_id, kind));
-            }
-            FromScriptMsg::HideIME => {
-                self.embedder_proxy.send(EmbedderMsg::HideIME(source_top_ctx_id));
-            }
         }
     }
 
@@ -1727,23 +1695,6 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         }
     }
 
-    fn handle_alert(&mut self,
-                    top_level_browsing_context_id: TopLevelBrowsingContextId,
-                    _message: String,
-                    sender: IpcSender<bool>) {
-        // FIXME: forward alert event to embedder
-        // https://github.com/servo/servo/issues/19992
-        let result = sender.send(true);
-        if let Err(e) = result {
-            let ctx_id = BrowsingContextId::from(top_level_browsing_context_id);
-            let pipeline_id = match self.browsing_contexts.get(&ctx_id) {
-                Some(ctx) => ctx.pipeline_id,
-                None => return warn!("Alert sent for unknown browsing context."),
-            };
-            self.handle_send_error(pipeline_id, e);
-        }
-    }
-
     fn handle_load_url_msg(&mut self, top_level_browsing_context_id: TopLevelBrowsingContextId, source_id: PipelineId,
                            load_data: LoadData, replace: bool) {
         self.load_url(top_level_browsing_context_id, source_id, load_data, replace);
@@ -2451,8 +2402,8 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
 
         entries.extend(session_history.future.iter().rev()
             .scan(current_load_data.clone(), &resolve_load_data_future));
-
-        let msg = EmbedderMsg::HistoryChanged(top_level_browsing_context_id, entries, current_index);
+        let urls = entries.iter().map(|entry| entry.url.clone()).collect();
+        let msg = EmbedderMsg::HistoryChanged(top_level_browsing_context_id, urls, current_index);
         self.embedder_proxy.send(msg);
     }
 
diff --git a/components/constellation/lib.rs b/components/constellation/lib.rs
index 5ae86080300..1fd6662d405 100644
--- a/components/constellation/lib.rs
+++ b/components/constellation/lib.rs
@@ -14,7 +14,7 @@ extern crate clipboard;
 extern crate compositing;
 extern crate debugger;
 extern crate devtools_traits;
-#[cfg(all(not(target_os = "windows"), not(target_os = "ios")))]
+#[cfg(not(target_os = "ios"))]
 extern crate embedder_traits;
 extern crate euclid;
 #[cfg(all(not(target_os = "windows"), not(target_os = "ios")))]
diff --git a/components/embedder_traits/Cargo.toml b/components/embedder_traits/Cargo.toml
index 9146893b13d..eb8bc420db6 100644
--- a/components/embedder_traits/Cargo.toml
+++ b/components/embedder_traits/Cargo.toml
@@ -13,4 +13,11 @@ path = "lib.rs"
 tests = []
 
 [dependencies]
+ipc-channel = "0.10"
 lazy_static = "1"
+log = "0.4"
+msg = {path = "../msg"}
+serde = "1.0"
+servo_url = {path = "../url"}
+style_traits = {path = "../style_traits"}
+webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}
diff --git a/components/embedder_traits/lib.rs b/components/embedder_traits/lib.rs
index aa8a3c0e111..6650c553946 100644
--- a/components/embedder_traits/lib.rs
+++ b/components/embedder_traits/lib.rs
@@ -2,6 +2,146 @@
  * 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/. */
 
-#[macro_use] extern crate lazy_static;
+extern crate ipc_channel;
+#[macro_use]
+extern crate lazy_static;
+#[macro_use]
+extern crate log;
+extern crate msg;
+#[macro_use]
+extern crate serde;
+extern crate servo_url;
+extern crate style_traits;
+extern crate webrender_api;
 
 pub mod resources;
+
+use ipc_channel::ipc::IpcSender;
+use msg::constellation_msg::{InputMethodType, Key, KeyModifiers, KeyState, TopLevelBrowsingContextId};
+use servo_url::ServoUrl;
+use std::fmt::{Debug, Error, Formatter};
+use std::sync::mpsc::{Receiver, Sender};
+use style_traits::cursor::CursorKind;
+use webrender_api::{DeviceIntPoint, DeviceUintSize};
+
+
+/// Used to wake up the event loop, provided by the servo port/embedder.
+pub trait EventLoopWaker : 'static + Send {
+    fn clone(&self) -> Box<EventLoopWaker + Send>;
+    fn wake(&self);
+}
+
+/// Sends messages to the embedder.
+pub struct EmbedderProxy {
+    pub sender: Sender<EmbedderMsg>,
+    pub event_loop_waker: Box<EventLoopWaker>,
+}
+
+impl EmbedderProxy {
+    pub fn send(&self, msg: EmbedderMsg) {
+        // Send a message and kick the OS event loop awake.
+        if let Err(err) = self.sender.send(msg) {
+            warn!("Failed to send response ({}).", err);
+        }
+        self.event_loop_waker.wake();
+    }
+}
+
+impl Clone for EmbedderProxy {
+    fn clone(&self) -> EmbedderProxy {
+        EmbedderProxy {
+            sender: self.sender.clone(),
+            event_loop_waker: self.event_loop_waker.clone(),
+        }
+    }
+}
+
+/// The port that the embedder receives messages on.
+pub struct EmbedderReceiver {
+    pub receiver: Receiver<EmbedderMsg>
+}
+
+impl EmbedderReceiver {
+    pub fn try_recv_embedder_msg(&mut self) -> Option<EmbedderMsg> {
+        self.receiver.try_recv().ok()
+    }
+    pub fn recv_embedder_msg(&mut self) -> EmbedderMsg {
+        self.receiver.recv().unwrap()
+    }
+}
+
+#[derive(Deserialize, Serialize)]
+pub enum EmbedderMsg {
+    /// A status message to be displayed by the browser chrome.
+    Status(TopLevelBrowsingContextId, Option<String>),
+    /// Alerts the embedder that the current page has changed its title.
+    ChangePageTitle(TopLevelBrowsingContextId, Option<String>),
+    /// Move the window to a point
+    MoveTo(TopLevelBrowsingContextId, DeviceIntPoint),
+    /// Resize the window to size
+    ResizeTo(TopLevelBrowsingContextId, DeviceUintSize),
+    // Show an alert message.
+    Alert(TopLevelBrowsingContextId, String, IpcSender<()>),
+    /// Wether or not to follow a link
+    AllowNavigation(TopLevelBrowsingContextId, ServoUrl, IpcSender<bool>),
+    /// Sends an unconsumed key event back to the embedder.
+    KeyEvent(Option<TopLevelBrowsingContextId>, Option<char>, Key, KeyState, KeyModifiers),
+    /// Changes the cursor.
+    SetCursor(CursorKind),
+    /// A favicon was detected
+    NewFavicon(TopLevelBrowsingContextId, ServoUrl),
+    /// <head> tag finished parsing
+    HeadParsed(TopLevelBrowsingContextId),
+    /// The history state has changed.
+    HistoryChanged(TopLevelBrowsingContextId, Vec<ServoUrl>, usize),
+    /// Enter or exit fullscreen
+    SetFullscreenState(TopLevelBrowsingContextId, bool),
+    /// The load of a page has begun
+    LoadStart(TopLevelBrowsingContextId),
+    /// The load of a page has completed
+    LoadComplete(TopLevelBrowsingContextId),
+    /// A pipeline panicked. First string is the reason, second one is the backtrace.
+    Panic(TopLevelBrowsingContextId, String, Option<String>),
+    /// Open dialog to select bluetooth device.
+    GetSelectedBluetoothDevice(Vec<String>, IpcSender<Option<String>>),
+    /// Open file dialog to select files. Set boolean flag to true allows to select multiple files.
+    SelectFiles(Vec<FilterPattern>, bool, IpcSender<Option<Vec<String>>>),
+    /// Request to present an IME to the user when an editable element is focused.
+    ShowIME(TopLevelBrowsingContextId, InputMethodType),
+    /// Request to hide the IME when the editable element is blurred.
+    HideIME(TopLevelBrowsingContextId),
+    /// Servo has shut down
+    Shutdown,
+}
+
+impl Debug for EmbedderMsg {
+    fn fmt(&self, f: &mut Formatter) -> Result<(), Error> {
+        match *self {
+            EmbedderMsg::Status(..) => write!(f, "Status"),
+            EmbedderMsg::ChangePageTitle(..) => write!(f, "ChangePageTitle"),
+            EmbedderMsg::MoveTo(..) => write!(f, "MoveTo"),
+            EmbedderMsg::ResizeTo(..) => write!(f, "ResizeTo"),
+            EmbedderMsg::Alert(..) => write!(f, "Alert"),
+            EmbedderMsg::AllowNavigation(..) => write!(f, "AllowNavigation"),
+            EmbedderMsg::KeyEvent(..) => write!(f, "KeyEvent"),
+            EmbedderMsg::SetCursor(..) => write!(f, "SetCursor"),
+            EmbedderMsg::NewFavicon(..) => write!(f, "NewFavicon"),
+            EmbedderMsg::HeadParsed(..) => write!(f, "HeadParsed"),
+            EmbedderMsg::HistoryChanged(..) => write!(f, "HistoryChanged"),
+            EmbedderMsg::SetFullscreenState(..) => write!(f, "SetFullscreenState"),
+            EmbedderMsg::LoadStart(..) => write!(f, "LoadStart"),
+            EmbedderMsg::LoadComplete(..) => write!(f, "LoadComplete"),
+            EmbedderMsg::Panic(..) => write!(f, "Panic"),
+            EmbedderMsg::GetSelectedBluetoothDevice(..) => write!(f, "GetSelectedBluetoothDevice"),
+            EmbedderMsg::SelectFiles(..) => write!(f, "SelectFiles"),
+            EmbedderMsg::ShowIME(..) => write!(f, "ShowIME"),
+            EmbedderMsg::HideIME(..) => write!(f, "HideIME"),
+            EmbedderMsg::Shutdown => write!(f, "Shutdown"),
+        }
+    }
+}
+
+/// Filter for file selection;
+/// the `String` content is expected to be extension (e.g, "doc", without the prefixing ".")
+#[derive(Clone, Debug, Deserialize, Serialize)]
+pub struct FilterPattern(pub String);
diff --git a/components/net/Cargo.toml b/components/net/Cargo.toml
index 9ef3654f902..43c8b22c4c0 100644
--- a/components/net/Cargo.toml
+++ b/components/net/Cargo.toml
@@ -16,7 +16,6 @@ doctest = false
 base64 = "0.6"
 brotli = "1.0.6"
 cookie = "0.10"
-compositing = {path = "../compositing"}
 devtools_traits = {path = "../devtools_traits"}
 embedder_traits = { path = "../embedder_traits" }
 flate2 = "1"
diff --git a/components/net/filemanager_thread.rs b/components/net/filemanager_thread.rs
index 6926412d104..ab1afef374d 100644
--- a/components/net/filemanager_thread.rs
+++ b/components/net/filemanager_thread.rs
@@ -2,11 +2,11 @@
  * 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/. */
 
-use compositing::compositor_thread::{EmbedderMsg, EmbedderProxy};
+use embedder_traits::{EmbedderMsg, EmbedderProxy, FilterPattern};
 use ipc_channel::ipc::{self, IpcSender};
 use mime_guess::guess_mime_type_opt;
 use net_traits::blob_url_store::{BlobBuf, BlobURLStoreError};
-use net_traits::filemanager_thread::{FileManagerResult, FileManagerThreadMsg, FileOrigin, FilterPattern};
+use net_traits::filemanager_thread::{FileManagerResult, FileManagerThreadMsg, FileOrigin};
 use net_traits::filemanager_thread::{FileManagerThreadError, ReadFileProgress, RelativePos, SelectedFile};
 use servo_config::prefs::PREFS;
 use std::collections::HashMap;
diff --git a/components/net/lib.rs b/components/net/lib.rs
index a8d802ae49f..cdeb7d54595 100644
--- a/components/net/lib.rs
+++ b/components/net/lib.rs
@@ -6,7 +6,6 @@
 
 extern crate base64;
 extern crate brotli;
-extern crate compositing;
 extern crate cookie as cookie_rs;
 extern crate devtools_traits;
 extern crate embedder_traits;
diff --git a/components/net/resource_thread.rs b/components/net/resource_thread.rs
index d00c0323f38..ffcdccebfe9 100644
--- a/components/net/resource_thread.rs
+++ b/components/net/resource_thread.rs
@@ -3,12 +3,12 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 //! A thread that takes a URL and streams back the binary data.
-use compositing::compositor_thread::EmbedderProxy;
 use connector::{create_http_connector, create_ssl_client};
 use cookie;
 use cookie_rs;
 use cookie_storage::CookieStorage;
 use devtools_traits::DevtoolsControlMsg;
+use embedder_traits::EmbedderProxy;
 use embedder_traits::resources::{self, Resource};
 use fetch::cors_cache::CorsCache;
 use fetch::methods::{CancellationListener, FetchContext, fetch};
diff --git a/components/net/tests/filemanager_thread.rs b/components/net/tests/filemanager_thread.rs
index d71c9f30187..8612bdae672 100644
--- a/components/net/tests/filemanager_thread.rs
+++ b/components/net/tests/filemanager_thread.rs
@@ -3,10 +3,11 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use create_embedder_proxy;
+use embedder_traits::FilterPattern;
 use ipc_channel::ipc;
 use net::filemanager_thread::FileManager;
 use net_traits::blob_url_store::BlobURLStoreError;
-use net_traits::filemanager_thread::{FilterPattern, FileManagerThreadMsg, FileManagerThreadError, ReadFileProgress};
+use net_traits::filemanager_thread::{FileManagerThreadMsg, FileManagerThreadError, ReadFileProgress};
 use servo_config::prefs::{PrefValue, PREFS};
 use std::fs::File;
 use std::io::Read;
diff --git a/components/net/tests/main.rs b/components/net/tests/main.rs
index a644a6a2fd4..1a7d5c462a5 100644
--- a/components/net/tests/main.rs
+++ b/components/net/tests/main.rs
@@ -4,7 +4,6 @@
 
 #![cfg(test)]
 
-extern crate compositing;
 extern crate cookie as cookie_rs;
 extern crate devtools_traits;
 extern crate embedder_traits;
@@ -35,8 +34,8 @@ mod mime_classifier;
 mod resource_thread;
 mod subresource_integrity;
 
-use compositing::compositor_thread::{EmbedderProxy, EventLoopWaker};
 use devtools_traits::DevtoolsControlMsg;
+use embedder_traits::{EmbedderProxy, EventLoopWaker};
 use embedder_traits::resources::{self, Resource};
 use hyper::server::{Handler, Listening, Server};
 use net::connector::create_ssl_client;
diff --git a/components/net_traits/filemanager_thread.rs b/components/net_traits/filemanager_thread.rs
index a9cb76bf98a..fa0ac23d8f5 100644
--- a/components/net_traits/filemanager_thread.rs
+++ b/components/net_traits/filemanager_thread.rs
@@ -3,6 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use blob_url_store::{BlobBuf, BlobURLStoreError};
+use embedder_traits::FilterPattern;
 use ipc_channel::ipc::IpcSender;
 use num_traits::ToPrimitive;
 use std::cmp::{max, min};
@@ -110,11 +111,6 @@ pub struct SelectedFile {
     pub type_string: String,
 }
 
-/// Filter for file selection;
-/// the `String` content is expected to be extension (e.g, "doc", without the prefixing ".")
-#[derive(Clone, Debug, Deserialize, Serialize)]
-pub struct FilterPattern(pub String);
-
 #[derive(Deserialize, Serialize)]
 pub enum FileManagerThreadMsg {
     /// Select a single file. Last field is pre-selected file path for testing
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index 3b6b92246f1..74f495b8867 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -88,6 +88,7 @@ use dom::webglcontextevent::WebGLContextEvent;
 use dom::window::{ReflowReason, Window};
 use dom::windowproxy::WindowProxy;
 use dom_struct::dom_struct;
+use embedder_traits::EmbedderMsg;
 use encoding_rs::{Encoding, UTF_8};
 use euclid::Point2D;
 use fetch::FetchCanceller;
@@ -855,7 +856,8 @@ impl Document {
 
             // Notify the embedder to hide the input method.
             if elem.input_method_type().is_some() {
-                self.send_to_constellation(ScriptMsg::HideIME);
+                let top_level_browsing_context_id = self.window().top_level_browsing_context_id();
+                self.send_to_embedder(EmbedderMsg::HideIME(top_level_browsing_context_id));
             }
         }
 
@@ -869,12 +871,13 @@ impl Document {
             // Update the focus state for all elements in the focus chain.
             // https://html.spec.whatwg.org/multipage/#focus-chain
             if focus_type == FocusType::Element {
-                self.send_to_constellation(ScriptMsg::Focus);
+                self.window().send_to_constellation(ScriptMsg::Focus);
             }
 
             // Notify the embedder to display an input method.
             if let Some(kind) = elem.input_method_type() {
-                self.send_to_constellation(ScriptMsg::ShowIME(kind));
+                let top_level_browsing_context_id = self.window().top_level_browsing_context_id();
+                self.send_to_embedder(EmbedderMsg::ShowIME(top_level_browsing_context_id, kind));
             }
         }
     }
@@ -882,14 +885,23 @@ impl Document {
     /// Handles any updates when the document's title has changed.
     pub fn title_changed(&self) {
         if self.browsing_context().is_some() {
-            self.send_title_to_constellation();
+            self.send_title_to_embedder();
         }
     }
 
     /// Sends this document's title to the constellation.
-    pub fn send_title_to_constellation(&self) {
-        let title = Some(String::from(self.Title()));
-        self.send_to_constellation(ScriptMsg::SetTitle(title));
+    pub fn send_title_to_embedder(&self) {
+        let window = self.window();
+        if window.is_top_level() {
+            let title = Some(String::from(self.Title()));
+            let top_level_browsing_context_id = window.top_level_browsing_context_id();
+            self.send_to_embedder(EmbedderMsg::ChangePageTitle(top_level_browsing_context_id, title));
+        }
+    }
+
+    fn send_to_embedder(&self, msg: EmbedderMsg) {
+        let window = self.window();
+        window.send_to_embedder(msg);
     }
 
     pub fn dirty_all_nodes(&self) {
@@ -1352,8 +1364,9 @@ impl Document {
         }
 
         if cancel_state == EventDefault::Allowed {
-            let msg = ScriptMsg::SendKeyEvent(ch, key, state, modifiers);
-            self.send_to_constellation(msg);
+            let top_level_browsing_context_id = self.window().top_level_browsing_context_id();
+            let msg = EmbedderMsg::KeyEvent(Some(top_level_browsing_context_id), ch, key, state, modifiers);
+            self.send_to_embedder(msg);
 
             // This behavior is unspecced
             // We are supposed to dispatch synthetic click activation for Space and/or Return,
@@ -1488,7 +1501,7 @@ impl Document {
             // repeated rAF.
 
             let event = ScriptMsg::ChangeRunningAnimationsState(AnimationState::AnimationCallbacksPresent);
-            self.send_to_constellation(event);
+            self.window().send_to_constellation(event);
         }
 
         ident
@@ -1559,7 +1572,7 @@ impl Document {
                 );
             }
             let event = ScriptMsg::ChangeRunningAnimationsState(AnimationState::NoAnimationCallbacksPresent);
-            self.send_to_constellation(event);
+            self.window().send_to_constellation(event);
         }
 
         // Update the counter of spurious animation frames.
@@ -2009,7 +2022,7 @@ impl Document {
     }
 
     pub fn notify_constellation_load(&self) {
-        self.send_to_constellation(ScriptMsg::LoadComplete);
+        self.window().send_to_constellation(ScriptMsg::LoadComplete);
     }
 
     pub fn set_current_parser(&self, script: Option<&ServoParser>) {
@@ -2167,11 +2180,6 @@ impl Document {
         registry.lookup_definition(local_name, is)
     }
 
-    fn send_to_constellation(&self, msg: ScriptMsg) {
-        let global_scope = self.window.upcast::<GlobalScope>();
-        global_scope.script_to_constellation_chan().send(msg).unwrap();
-    }
-
     pub fn increment_throw_on_dynamic_markup_insertion_counter(&self) {
         let counter = self.throw_on_dynamic_markup_insertion_counter.get();
         self.throw_on_dynamic_markup_insertion_counter.set(counter + 1);
@@ -2787,8 +2795,9 @@ impl Document {
         let window = self.window();
         // Step 6
         if !error {
-            let event = ScriptMsg::SetFullscreenState(true);
-            self.send_to_constellation(event);
+            let top_level_browsing_context_id = self.window().top_level_browsing_context_id();
+            let event = EmbedderMsg::SetFullscreenState(top_level_browsing_context_id, true);
+            self.send_to_embedder(event);
         }
 
         let pipeline_id = self.window().pipeline_id();
@@ -2822,8 +2831,9 @@ impl Document {
 
         let window = self.window();
         // Step 8
-        let event = ScriptMsg::SetFullscreenState(false);
-        self.send_to_constellation(event);
+        let top_level_browsing_context_id = self.window().top_level_browsing_context_id();
+        let event = EmbedderMsg::SetFullscreenState(top_level_browsing_context_id, true);
+        self.send_to_embedder(event);
 
         // Step 9
         let trusted_element = Trusted::new(element.r());
diff --git a/components/script/dom/htmlbodyelement.rs b/components/script/dom/htmlbodyelement.rs
index c3ac339e33c..51ed2fcd0ea 100644
--- a/components/script/dom/htmlbodyelement.rs
+++ b/components/script/dom/htmlbodyelement.rs
@@ -12,13 +12,12 @@ use dom::bindings::str::DOMString;
 use dom::document::Document;
 use dom::element::{AttributeMutation, Element, RawLayoutElementHelpers};
 use dom::eventtarget::EventTarget;
-use dom::globalscope::GlobalScope;
 use dom::htmlelement::HTMLElement;
 use dom::node::{Node, document_from_node, window_from_node};
 use dom::virtualmethods::VirtualMethods;
 use dom_struct::dom_struct;
+use embedder_traits::EmbedderMsg;
 use html5ever::{LocalName, Prefix};
-use script_traits::ScriptMsg;
 use servo_url::ServoUrl;
 use style::attr::AttrValue;
 use time;
@@ -151,8 +150,11 @@ impl VirtualMethods for HTMLBodyElement {
         let window = window_from_node(self);
         let document = window.Document();
         document.set_reflow_timeout(time::precise_time_ns() + INITIAL_REFLOW_DELAY);
-        let event = ScriptMsg::HeadParsed;
-        window.upcast::<GlobalScope>().script_to_constellation_chan().send(event).unwrap();
+        if window.is_top_level() {
+            let top_level_browsing_context_id = window.top_level_browsing_context_id();
+            let msg = EmbedderMsg::HeadParsed(top_level_browsing_context_id);
+            window.send_to_embedder(msg);
+        }
     }
 
     fn parse_plain_attribute(&self, name: &LocalName, value: DOMString) -> AttrValue {
diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index ab7d55d5b9a..f2d83fa4d54 100755
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -38,12 +38,13 @@ use dom::validation::Validatable;
 use dom::validitystate::ValidationFlags;
 use dom::virtualmethods::VirtualMethods;
 use dom_struct::dom_struct;
+use embedder_traits::FilterPattern;
 use html5ever::{LocalName, Prefix};
 use mime_guess;
 use msg::constellation_msg::InputMethodType;
 use net_traits::{CoreResourceMsg, IpcSend};
 use net_traits::blob_url_store::get_blob_origin;
-use net_traits::filemanager_thread::{FileManagerThreadMsg, FilterPattern};
+use net_traits::filemanager_thread::FileManagerThreadMsg;
 use profile_traits::ipc;
 use script_layout_interface::rpc::TextIndexResponse;
 use script_traits::ScriptToConstellationChan;
diff --git a/components/script/dom/htmllinkelement.rs b/components/script/dom/htmllinkelement.rs
index f3f82cb5ce1..c05bd0ee0f6 100644
--- a/components/script/dom/htmllinkelement.rs
+++ b/components/script/dom/htmllinkelement.rs
@@ -16,15 +16,14 @@ use dom::document::Document;
 use dom::domtokenlist::DOMTokenList;
 use dom::element::{AttributeMutation, Element, ElementCreator};
 use dom::element::{cors_setting_for_element, reflect_cross_origin_attribute, set_cross_origin_attribute};
-use dom::globalscope::GlobalScope;
 use dom::htmlelement::HTMLElement;
 use dom::node::{Node, UnbindContext, document_from_node, window_from_node};
 use dom::stylesheet::StyleSheet as DOMStyleSheet;
 use dom::virtualmethods::VirtualMethods;
 use dom_struct::dom_struct;
+use embedder_traits::EmbedderMsg;
 use html5ever::{LocalName, Prefix};
 use net_traits::ReferrerPolicy;
-use script_traits::ScriptMsg;
 use servo_arc::Arc;
 use std::borrow::ToOwned;
 use std::cell::Cell;
@@ -306,8 +305,13 @@ impl HTMLLinkElement {
         let document = document_from_node(self);
         match document.base_url().join(href) {
             Ok(url) => {
-                let event = ScriptMsg::NewFavicon(url.clone());
-                document.window().upcast::<GlobalScope>().script_to_constellation_chan().send(event).unwrap();
+                let window = document.window();
+                if window.is_top_level() {
+                    let top_level_browsing_context_id = window.top_level_browsing_context_id();
+                    let msg = EmbedderMsg::NewFavicon(top_level_browsing_context_id, url.clone());
+                    window.send_to_embedder(msg);
+                }
+
             }
             Err(e) => debug!("Parsing url {} failed: {}", href, e)
         }
diff --git a/components/script/dom/window.rs b/components/script/dom/window.rs
index 00f65b60611..b80a87b7627 100644
--- a/components/script/dom/window.rs
+++ b/components/script/dom/window.rs
@@ -48,6 +48,7 @@ use dom::windowproxy::WindowProxy;
 use dom::worklet::Worklet;
 use dom::workletglobalscope::WorkletGlobalScopeType;
 use dom_struct::dom_struct;
+use embedder_traits::EmbedderMsg;
 use euclid::{Point2D, Vector2D, Rect, Size2D, TypedPoint2D, TypedScale, TypedSize2D};
 use fetch;
 use ipc_channel::ipc::IpcSender;
@@ -58,7 +59,7 @@ use js::jsval::UndefinedValue;
 use js::rust::HandleValue;
 use layout_image::fetch_image_for_layout;
 use microtask::MicrotaskQueue;
-use msg::constellation_msg::PipelineId;
+use msg::constellation_msg::{PipelineId, TopLevelBrowsingContextId};
 use net_traits::{ResourceThreads, ReferrerPolicy};
 use net_traits::image_cache::{ImageCache, ImageResponder, ImageResponse};
 use net_traits::image_cache::{PendingImageId, PendingImageResponse};
@@ -114,8 +115,6 @@ use task_source::performance_timeline::PerformanceTimelineTaskSource;
 use task_source::user_interaction::UserInteractionTaskSource;
 use time;
 use timers::{IsInterval, TimerCallback};
-#[cfg(any(target_os = "macos", target_os = "linux", target_os = "windows"))]
-use tinyfiledialogs::{self, MessageBoxIcon};
 use url::Position;
 use webdriver_handlers::jsval_to_webdriver;
 use webrender_api::{ExternalScrollId, DeviceIntPoint, DeviceUintSize, DocumentId};
@@ -356,6 +355,11 @@ impl Window {
         self.parent_info
     }
 
+    pub fn top_level_browsing_context_id(&self) -> TopLevelBrowsingContextId {
+        let window_proxy = self.window_proxy.get().unwrap();
+         window_proxy.top_level_browsing_context_id()
+    }
+
     pub fn new_script_pair(&self) -> (Box<ScriptChan + Send>, Box<ScriptPort + Send>) {
         let (tx, rx) = channel();
         (Box::new(SendableMainThreadScriptChan(tx)), Box::new(rx))
@@ -444,18 +448,6 @@ impl Window {
     }
 }
 
-#[cfg(any(target_os = "macos", target_os = "linux", target_os = "windows"))]
-fn display_alert_dialog(message: &str) {
-    if !opts::get().headless {
-        tinyfiledialogs::message_box_ok("Alert!", message, MessageBoxIcon::Warning);
-    }
-}
-
-#[cfg(not(any(target_os = "macos", target_os = "linux", target_os = "windows")))]
-fn display_alert_dialog(_message: &str) {
-    // tinyfiledialogs not supported on Android
-}
-
 // https://html.spec.whatwg.org/multipage/#atob
 pub fn base64_btoa(input: DOMString) -> Fallible<DOMString> {
     // "The btoa() method must throw an InvalidCharacterError exception if
@@ -541,14 +533,12 @@ impl WindowMethods for Window {
             stdout.flush().unwrap();
             stderr.flush().unwrap();
         }
-
         let (sender, receiver) = ProfiledIpc::channel(self.global().time_profiler_chan().clone()).unwrap();
-        self.send_to_constellation(ScriptMsg::Alert(s.to_string(), sender));
-
-        let should_display_alert_dialog = receiver.recv().unwrap();
-        if should_display_alert_dialog {
-            display_alert_dialog(&s);
-        }
+        let window_proxy = self.window_proxy.get().unwrap();
+        let top_level_browsing_context_id = window_proxy.top_level_browsing_context_id();
+        let msg = EmbedderMsg::Alert(top_level_browsing_context_id, s.to_string(), sender);
+        self.send_to_embedder(msg);
+        receiver.recv().unwrap();
     }
 
     // https://html.spec.whatwg.org/multipage/#dom-window-closed
@@ -937,7 +927,8 @@ impl WindowMethods for Window {
         //TODO determine if this operation is allowed
         let dpr = self.device_pixel_ratio();
         let size = TypedSize2D::new(width, height).to_f32() * dpr;
-        self.send_to_constellation(ScriptMsg::ResizeTo(size.to_u32()));
+        let top_level_browsing_context_id = self.top_level_browsing_context_id();
+        self.send_to_embedder(EmbedderMsg::ResizeTo(top_level_browsing_context_id, size.to_u32()));
     }
 
     // https://drafts.csswg.org/cssom-view/#dom-window-resizeby
@@ -953,7 +944,10 @@ impl WindowMethods for Window {
         //TODO determine if this operation is allowed
         let dpr = self.device_pixel_ratio();
         let point = TypedPoint2D::new(x, y).to_f32() * dpr;
-        self.send_to_constellation(ScriptMsg::MoveTo(point.to_i32()));
+        let window_proxy = self.window_proxy.get().unwrap();
+        let top_level_browsing_context_id = window_proxy.top_level_browsing_context_id();
+        let msg = EmbedderMsg::MoveTo(top_level_browsing_context_id, point.to_i32());
+        self.send_to_embedder(msg);
     }
 
     // https://drafts.csswg.org/cssom-view/#dom-window-moveby
@@ -1742,7 +1736,11 @@ impl Window {
         self.navigation_start_precise.set(time::precise_time_ns());
     }
 
-    fn send_to_constellation(&self, msg: ScriptMsg) {
+    pub fn send_to_embedder(&self, msg: EmbedderMsg) {
+        self.send_to_constellation(ScriptMsg::ForwardToEmbedder(msg));
+    }
+
+    pub fn send_to_constellation(&self, msg: ScriptMsg) {
         self.upcast::<GlobalScope>()
             .script_to_constellation_chan()
             .send(msg)
diff --git a/components/script/lib.rs b/components/script/lib.rs
index bee088aa5e0..cf020ab9ac6 100644
--- a/components/script/lib.rs
+++ b/components/script/lib.rs
@@ -93,7 +93,7 @@ extern crate style;
 extern crate style_traits;
 extern crate swapper;
 extern crate time;
-#[cfg(any(target_os = "macos", target_os = "linux", target_os = "windows"))]
+#[cfg(target_os = "linux")]
 extern crate tinyfiledialogs;
 extern crate unicode_segmentation;
 extern crate url;
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 613918f6a76..a118562a234 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -62,6 +62,7 @@ use dom::windowproxy::WindowProxy;
 use dom::worker::TrustedWorkerAddress;
 use dom::worklet::WorkletThreadPool;
 use dom::workletglobalscope::WorkletGlobalScopeInit;
+use embedder_traits::EmbedderMsg;
 use euclid::{Point2D, Vector2D, Rect};
 use fetch::FetchCanceller;
 use hyper::header::{ContentType, HttpDate, Headers, LastModified};
@@ -1822,7 +1823,7 @@ impl ScriptThread {
             Some(document) => document,
             None => return warn!("Message sent to closed pipeline {}.", pipeline_id),
         };
-        document.send_title_to_constellation();
+        document.send_title_to_embedder();
     }
 
     /// Handles a request to exit a pipeline and shut down layout.
@@ -2282,6 +2283,8 @@ impl ScriptThread {
                     Some(document) => document,
                     None => return warn!("Message sent to closed pipeline {}.", pipeline_id),
                 };
+                let window = document.window();
+                let top_level_browsing_context_id = window.top_level_browsing_context_id();
 
                 // Get the previous target temporarily
                 let prev_mouse_over_target = self.topmost_mouse_over_target.get();
@@ -2310,9 +2313,8 @@ impl ScriptThread {
                                                let url = document.url();
                                                url.join(&value).map(|url| url.to_string()).ok()
                                            });
-
-                        let event = ScriptMsg::NodeStatus(status);
-                        self.script_sender.send((pipeline_id, event)).unwrap();
+                        let event = EmbedderMsg::Status(top_level_browsing_context_id, status);
+                        window.send_to_embedder(event);
 
                         state_already_changed = true;
                     }
@@ -2325,8 +2327,8 @@ impl ScriptThread {
                                                .inclusive_ancestors()
                                                .filter_map(DomRoot::downcast::<HTMLAnchorElement>)
                                                .next() {
-                            let event = ScriptMsg::NodeStatus(None);
-                            self.script_sender.send((pipeline_id, event)).unwrap();
+                            let event = EmbedderMsg::Status(top_level_browsing_context_id, None);
+                            window.send_to_embedder(event);
                         }
                     }
                 }
diff --git a/components/script_traits/Cargo.toml b/components/script_traits/Cargo.toml
index 2d3c47c14b7..a5ae8cf0d7e 100644
--- a/components/script_traits/Cargo.toml
+++ b/components/script_traits/Cargo.toml
@@ -14,6 +14,7 @@ bluetooth_traits = {path = "../bluetooth_traits"}
 canvas_traits = {path = "../canvas_traits"}
 cookie = "0.10"
 devtools_traits = {path = "../devtools_traits"}
+embedder_traits = {path = "../embedder_traits"}
 euclid = "0.17"
 gfx_traits = {path = "../gfx_traits"}
 hyper = "0.10"
@@ -34,3 +35,6 @@ time = "0.1.12"
 url = "1.2"
 webrender_api = {git = "https://github.com/servo/webrender", features = ["ipc"]}
 webvr_traits = {path = "../webvr_traits"}
+
+[dev-dependencies]
+embedder_traits = { path = "../embedder_traits", features = ["tests"]}
diff --git a/components/script_traits/lib.rs b/components/script_traits/lib.rs
index 9ecda6625d6..6075cc6fc43 100644
--- a/components/script_traits/lib.rs
+++ b/components/script_traits/lib.rs
@@ -13,6 +13,7 @@ extern crate bluetooth_traits;
 extern crate canvas_traits;
 extern crate cookie as cookie_rs;
 extern crate devtools_traits;
+extern crate embedder_traits;
 extern crate euclid;
 extern crate gfx_traits;
 extern crate hyper;
@@ -702,6 +703,8 @@ pub enum ConstellationMsg {
     NewBrowser(ServoUrl, IpcSender<TopLevelBrowsingContextId>),
     /// Close a top level browsing context.
     CloseBrowser(TopLevelBrowsingContextId),
+    /// Panic a top level browsing context.
+    SendError(Option<TopLevelBrowsingContextId>, String),
     /// Make browser visible.
     SelectBrowser(TopLevelBrowsingContextId),
     /// Forward an event to the script task of the given pipeline.
@@ -730,6 +733,7 @@ impl fmt::Debug for ConstellationMsg {
             WebVREvents(..) => "WebVREvents",
             NewBrowser(..) => "NewBrowser",
             CloseBrowser(..) => "CloseBrowser",
+            SendError(..) => "SendError",
             SelectBrowser(..) => "SelectBrowser",
             ForwardEvent(..) => "ForwardEvent",
             SetCursor(..) => "SetCursor",
diff --git a/components/script_traits/script_msg.rs b/components/script_traits/script_msg.rs
index ad437b09d8d..c9cb879f1c2 100644
--- a/components/script_traits/script_msg.rs
+++ b/components/script_traits/script_msg.rs
@@ -12,11 +12,11 @@ use WorkerGlobalScopeInit;
 use WorkerScriptLoadOrigin;
 use canvas_traits::canvas::{CanvasMsg, CanvasId};
 use devtools_traits::{ScriptToDevtoolsControlMsg, WorkerId};
+use embedder_traits::EmbedderMsg;
 use euclid::{Size2D, TypedSize2D};
 use gfx_traits::Epoch;
 use ipc_channel::ipc::{IpcReceiver, IpcSender};
 use msg::constellation_msg::{BrowsingContextId, HistoryStateId, PipelineId, TraversalDirection};
-use msg::constellation_msg::{InputMethodType, Key, KeyModifiers, KeyState};
 use net_traits::CoreResourceMsg;
 use net_traits::request::RequestInit;
 use net_traits::storage_thread::StorageType;
@@ -83,6 +83,8 @@ pub enum LogEntry {
 /// Messages from the script to the constellation.
 #[derive(Deserialize, Serialize)]
 pub enum ScriptMsg {
+    /// Forward a message to the embedder.
+    ForwardToEmbedder(EmbedderMsg),
     /// Requests are sent to constellation and fetches are checked manually
     /// for cross-origin loads
     InitiateNavigateRequest(RequestInit, /* cancellation_chan */ IpcReceiver<()>),
@@ -104,8 +106,6 @@ pub enum ScriptMsg {
     GetParentInfo(PipelineId, IpcSender<Option<PipelineId>>),
     /// Get the nth child browsing context ID for a given browsing context, sorted in tree order.
     GetChildBrowsingContextId(BrowsingContextId, usize, IpcSender<Option<BrowsingContextId>>),
-    /// <head> tag finished parsing
-    HeadParsed,
     /// All pending loads are complete, and the `load` event for this pipeline
     /// has been dispatched.
     LoadComplete,
@@ -124,10 +124,6 @@ pub enum ScriptMsg {
     ReplaceHistoryState(HistoryStateId, ServoUrl),
     /// Gets the length of the joint session history from the constellation.
     JointSessionHistoryLength(IpcSender<u32>),
-    /// Favicon detected
-    NewFavicon(ServoUrl),
-    /// Status message to be displayed in the chrome, eg. a link URL on mouseover.
-    NodeStatus(Option<String>),
     /// Notification that this iframe should be removed.
     /// Returns a list of pipelines which were closed.
     RemoveIFrame(BrowsingContextId, IpcSender<Vec<PipelineId>>),
@@ -147,17 +143,6 @@ pub enum ScriptMsg {
     SetDocumentState(DocumentState),
     /// Update the pipeline Url, which can change after redirections.
     SetFinalUrl(ServoUrl),
-    /// Check if an alert dialog box should be presented
-    Alert(String, IpcSender<bool>),
-    /// Set title of current page
-    /// <https://html.spec.whatwg.org/multipage/#document.title>
-    SetTitle(Option<String>),
-    /// Send a key event
-    SendKeyEvent(Option<char>, Key, KeyState, KeyModifiers),
-    /// Move the window to a point
-    MoveTo(DeviceIntPoint),
-    /// Resize the window to size
-    ResizeTo(DeviceUintSize),
     /// Script has handled a touch event, and either prevented or allowed default actions.
     TouchEventProcessed(EventResult),
     /// A log entry, with the top-level browsing context id and thread name
@@ -171,18 +156,12 @@ pub enum ScriptMsg {
     ForwardDOMMessage(DOMMessage, ServoUrl),
     /// Store the data required to activate a service worker for the given scope
     RegisterServiceWorker(ScopeThings, ServoUrl),
-    /// Enter or exit fullscreen
-    SetFullscreenState(bool),
     /// Get Window Informations size and position
     GetClientWindow(IpcSender<(DeviceUintSize, DeviceIntPoint)>),
     /// Get the screen size (pixel)
     GetScreenSize(IpcSender<(DeviceUintSize)>),
     /// Get the available screen size (pixel)
     GetScreenAvailSize(IpcSender<(DeviceUintSize)>),
-    /// Request to present an IME to the user when an editable element is focused.
-    ShowIME(InputMethodType),
-    /// Request to hide the IME when the editable element is blurred.
-    HideIME,
     /// Requests that the compositor shut down.
     Exit,
 }
@@ -191,6 +170,7 @@ impl fmt::Debug for ScriptMsg {
     fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
         use self::ScriptMsg::*;
         let variant = match *self {
+            ForwardToEmbedder(..) => "ForwardToEmbedder",
             InitiateNavigateRequest(..) => "InitiateNavigateRequest",
             BroadcastStorageEvent(..) => "BroadcastStorageEvent",
             ChangeRunningAnimationsState(..) => "ChangeRunningAnimationsState",
@@ -200,7 +180,6 @@ impl fmt::Debug for ScriptMsg {
             GetBrowsingContextId(..) => "GetBrowsingContextId",
             GetParentInfo(..) => "GetParentInfo",
             GetChildBrowsingContextId(..) => "GetChildBrowsingContextId",
-            HeadParsed => "HeadParsed",
             LoadComplete => "LoadComplete",
             LoadUrl(..) => "LoadUrl",
             AbortLoadUrl => "AbortLoadUrl",
@@ -209,8 +188,6 @@ impl fmt::Debug for ScriptMsg {
             PushHistoryState(..) => "PushHistoryState",
             ReplaceHistoryState(..) => "ReplaceHistoryState",
             JointSessionHistoryLength(..) => "JointSessionHistoryLength",
-            NewFavicon(..) => "NewFavicon",
-            NodeStatus(..) => "NodeStatus",
             RemoveIFrame(..) => "RemoveIFrame",
             SetVisible(..) => "SetVisible",
             VisibilityChangeComplete(..) => "VisibilityChangeComplete",
@@ -220,23 +197,15 @@ impl fmt::Debug for ScriptMsg {
             ActivateDocument => "ActivateDocument",
             SetDocumentState(..) => "SetDocumentState",
             SetFinalUrl(..) => "SetFinalUrl",
-            Alert(..) => "Alert",
-            SetTitle(..) => "SetTitle",
-            SendKeyEvent(..) => "SendKeyEvent",
-            MoveTo(..) => "MoveTo",
-            ResizeTo(..) => "ResizeTo",
             TouchEventProcessed(..) => "TouchEventProcessed",
             LogEntry(..) => "LogEntry",
             DiscardDocument => "DiscardDocument",
             PipelineExited => "PipelineExited",
             ForwardDOMMessage(..) => "ForwardDOMMessage",
             RegisterServiceWorker(..) => "RegisterServiceWorker",
-            SetFullscreenState(..) => "SetFullscreenState",
             GetClientWindow(..) => "GetClientWindow",
             GetScreenSize(..) => "GetScreenSize",
             GetScreenAvailSize(..) => "GetScreenAvailSize",
-            ShowIME(..) => "ShowIME",
-            HideIME => "HideIME",
             Exit => "Exit",
         };
         write!(formatter, "ScriptMsg::{}", variant)
diff --git a/components/servo/lib.rs b/components/servo/lib.rs
index bc06dc84ca7..b532bd80b5f 100644
--- a/components/servo/lib.rs
+++ b/components/servo/lib.rs
@@ -73,13 +73,13 @@ use bluetooth_traits::BluetoothRequest;
 use canvas::gl_context::GLContextFactory;
 use canvas::webgl_thread::WebGLThreads;
 use compositing::{IOCompositor, ShutdownState, RenderNotifier};
-use compositing::compositor_thread::{self, CompositorProxy, CompositorReceiver, InitialCompositorState};
-use compositing::compositor_thread::{EmbedderMsg, EmbedderProxy, EmbedderReceiver};
+use compositing::compositor_thread::{CompositorProxy, CompositorReceiver, InitialCompositorState};
 use compositing::windowing::{WindowEvent, WindowMethods};
 use constellation::{Constellation, InitialConstellationState, UnprivilegedPipelineContent};
 use constellation::{FromCompositorLogger, FromScriptLogger};
 #[cfg(all(not(target_os = "windows"), not(target_os = "ios")))]
 use constellation::content_process_sandbox_profile;
+use embedder_traits::{EmbedderMsg, EmbedderProxy, EmbedderReceiver, EventLoopWaker};
 use env_logger::Builder as EnvLoggerBuilder;
 use euclid::Length;
 #[cfg(all(not(target_os = "windows"), not(target_os = "ios")))]
@@ -346,6 +346,13 @@ impl<Window> Servo<Window> where Window: WindowMethods + 'static {
                     warn!("Sending CloseBrowser message to constellation failed ({}).", e);
                 }
             }
+
+            WindowEvent::SendError(ctx, e) => {
+                let msg = ConstellationMsg::SendError(ctx, e);
+                if let Err(e) = self.constellation_chan.send(msg) {
+                    warn!("Sending CloseBrowser message to constellation failed ({}).", e);
+                }
+            }
         }
     }
 
@@ -417,7 +424,7 @@ impl<Window> Servo<Window> where Window: WindowMethods + 'static {
     }
 }
 
-fn create_embedder_channel(event_loop_waker: Box<compositor_thread::EventLoopWaker>)
+fn create_embedder_channel(event_loop_waker: Box<EventLoopWaker>)
     -> (EmbedderProxy, EmbedderReceiver) {
     let (sender, receiver) = channel();
     (EmbedderProxy {
@@ -429,7 +436,7 @@ fn create_embedder_channel(event_loop_waker: Box<compositor_thread::EventLoopWak
      })
 }
 
-fn create_compositor_channel(event_loop_waker: Box<compositor_thread::EventLoopWaker>)
+fn create_compositor_channel(event_loop_waker: Box<EventLoopWaker>)
     -> (CompositorProxy, CompositorReceiver) {
     let (sender, receiver) = channel();
     (CompositorProxy {
diff --git a/ports/servo/browser.rs b/ports/servo/browser.rs
index 6d83c59153d..a64ba44e088 100644
--- a/ports/servo/browser.rs
+++ b/ports/servo/browser.rs
@@ -5,12 +5,10 @@
 use euclid::{TypedPoint2D, TypedVector2D};
 use glutin_app::keyutils::{CMD_OR_CONTROL, CMD_OR_ALT};
 use glutin_app::window::{Window, LINE_HEIGHT};
-use servo::compositing::compositor_thread::EmbedderMsg;
 use servo::compositing::windowing::{WebRenderDebugOption, WindowEvent};
-use servo::ipc_channel::ipc::IpcSender;
+use servo::embedder_traits::{EmbedderMsg, FilterPattern};
 use servo::msg::constellation_msg::{Key, TopLevelBrowsingContextId as BrowserId};
 use servo::msg::constellation_msg::{KeyModifiers, KeyState, TraversalDirection};
-use servo::net_traits::filemanager_thread::FilterPattern;
 use servo::net_traits::pub_domains::is_reg_domain;
 use servo::script_traits::TouchEventType;
 use servo::servo_config::opts;
@@ -21,7 +19,8 @@ use std::mem;
 use std::rc::Rc;
 #[cfg(any(target_os = "macos", target_os = "linux", target_os = "windows"))]
 use std::thread;
-use tinyfiledialogs;
+#[cfg(any(target_os = "macos", target_os = "linux", target_os = "windows"))]
+use tinyfiledialogs::{self, MessageBoxIcon};
 
 pub struct Browser {
     current_url: Option<ServoUrl>,
@@ -260,6 +259,13 @@ impl Browser {
                 EmbedderMsg::ResizeTo(_browser_id, size) => {
                     self.window.set_inner_size(size);
                 }
+                EmbedderMsg::Alert(browser_id, message, sender) => {
+                    display_alert_dialog(message.to_owned());
+                    if let Err(e) = sender.send(()) {
+                        let reason = format!("Failed to send Alert response: {}", e);
+                        self.event_queue.push(WindowEvent::SendError(Some(browser_id), reason));
+                    }
+                }
                 EmbedderMsg::AllowNavigation(_browser_id, _url, response_chan) => {
                     if let Err(e) = response_chan.send(true) {
                         warn!("Failed to send allow_navigation() response: {}", e);
@@ -277,8 +283,8 @@ impl Browser {
                 EmbedderMsg::HeadParsed(_browser_id, ) => {
                     self.loading_state = Some(LoadingState::Loading);
                 }
-                EmbedderMsg::HistoryChanged(_browser_id, entries, current) => {
-                    self.current_url = Some(entries[current].url.clone());
+                EmbedderMsg::HistoryChanged(_browser_id, urls, current) => {
+                    self.current_url = Some(urls[current].clone());
                 }
                 EmbedderMsg::SetFullscreenState(_browser_id, state) => {
                     self.window.set_fullscreen(state);
@@ -295,13 +301,22 @@ impl Browser {
                 EmbedderMsg::Panic(_browser_id, _reason, _backtrace) => {
                 },
                 EmbedderMsg::GetSelectedBluetoothDevice(devices, sender) => {
-                    platform_get_selected_devices(devices, sender);
+                    let selected = platform_get_selected_devices(devices);
+                    if let Err(e) = sender.send(selected) {
+                        let reason = format!("Failed to send GetSelectedBluetoothDevice response: {}", e);
+                        self.event_queue.push(WindowEvent::SendError(None, reason));
+                    };
                 },
                 EmbedderMsg::SelectFiles(patterns, multiple_files, sender) => {
-                    if opts::get().headless {
-                        let _ = sender.send(None);
-                    }
-                    platform_get_selected_files(patterns, multiple_files, sender);
+                    let res = match (opts::get().headless,
+                                     platform_get_selected_files(patterns, multiple_files)) {
+                        (true, _) | (false, None) => sender.send(None),
+                        (false, Some(files)) => sender.send(Some(files))
+                    };
+                    if let Err(e) = res {
+                        let reason = format!("Failed to send SelectFiles response: {}", e);
+                        self.event_queue.push(WindowEvent::SendError(None, reason));
+                    };
                 }
                 EmbedderMsg::ShowIME(_browser_id, _kind) => {
                     debug!("ShowIME received");
@@ -315,8 +330,22 @@ impl Browser {
 
 }
 
+#[cfg(any(target_os = "macos", target_os = "linux", target_os = "windows"))]
+fn display_alert_dialog(message: String) {
+    if !opts::get().headless {
+        let _ = thread::Builder::new().name("display alert dialog".to_owned()).spawn(move || {
+            tinyfiledialogs::message_box_ok("Alert!", &message, MessageBoxIcon::Warning);
+        }).unwrap().join().expect("Thread spawning failed");
+    }
+}
+
+#[cfg(not(any(target_os = "macos", target_os = "linux", target_os = "windows")))]
+fn display_alert_dialog(_message: String) {
+    // tinyfiledialogs not supported on Android
+}
+
 #[cfg(target_os = "linux")]
-fn platform_get_selected_devices(devices: Vec<String>, sender: IpcSender<Option<String>>) {
+fn platform_get_selected_devices(devices: Vec<String>) -> Option<String> {
     let picker_name = "Choose a device";
 
     thread::Builder::new().name(picker_name.to_owned()).spawn(move || {
@@ -328,58 +357,54 @@ fn platform_get_selected_devices(devices: Vec<String>, sender: IpcSender<Option<
         match tinyfiledialogs::list_dialog("Choose a device", &["Id", "Name"], dialog_rows) {
             Some(device) => {
                 // The device string format will be "Address|Name". We need the first part of it.
-                let address = device.split("|").next().map(|s| s.to_string());
-                let _ = sender.send(address);
+                device.split("|").next().map(|s| s.to_string())
             },
             None => {
-                let _ = sender.send(None);
+                None
             }
         }
-    }).expect("Thread spawning failed");
+    }).unwrap().join().expect("Thread spawning failed")
 }
 
 #[cfg(not(target_os = "linux"))]
-fn platform_get_selected_devices(devices: Vec<String>, sender: IpcSender<Option<String>>) {
+fn platform_get_selected_devices(devices: Vec<String>) -> Option<String> {
     for device in devices {
         if let Some(address) = device.split("|").next().map(|s| s.to_string()) {
-            let _ = sender.send(Some(address));
+            return Some(address)
         }
     }
-    let _ = sender.send(None);
+    None
 }
 
 #[cfg(any(target_os = "macos", target_os = "linux", target_os = "windows"))]
 fn platform_get_selected_files(patterns: Vec<FilterPattern>,
-                               multiple_files: bool,
-                               sender: IpcSender<Option<Vec<String>>>) {
+                               multiple_files: bool)
+                               -> Option<Vec<String>> {
     let picker_name = if multiple_files { "Pick files" } else { "Pick a file" };
-
     thread::Builder::new().name(picker_name.to_owned()).spawn(move || {
-        let mut filter = vec![];
+        let mut filters = vec![];
         for p in patterns {
             let s = "*.".to_string() + &p.0;
-            filter.push(s)
+            filters.push(s)
         }
-
-        let filter_ref = &(filter.iter().map(|s| s.as_str()).collect::<Vec<&str>>()[..]);
-        let filter_opt = if filter.len() > 0 { Some((filter_ref, "")) } else { None };
+        let filter_ref = &(filters.iter().map(|s| s.as_str()).collect::<Vec<&str>>()[..]);
+        let filter_opt = if filters.len() > 0 { Some((filter_ref, "")) } else { None };
 
         if multiple_files {
-            let files = tinyfiledialogs::open_file_dialog_multi(picker_name, "", filter_opt);
-            let _ = sender.send(files);
+            tinyfiledialogs::open_file_dialog_multi(picker_name, "", filter_opt)
         } else {
             let file = tinyfiledialogs::open_file_dialog(picker_name, "", filter_opt);
-            let _ = sender.send(file.map(|x| vec![x]));
+            file.map(|x| vec![x])
         }
-    }).expect("Thread spawning failed");
+    }).unwrap().join().expect("Thread spawning failed")
 }
 
 #[cfg(not(any(target_os = "macos", target_os = "linux", target_os = "windows")))]
 fn platform_get_selected_files(_patterns: Vec<FilterPattern>,
-                               _multiple_files: bool,
-                               sender: IpcSender<Option<Vec<String>>>) {
+                               _multiple_files: bool)
+                               -> Option<Vec<String>> {
     warn!("File picker not implemented");
-    let _ = sender.send(None);
+    None
 }
 
 fn sanitize_url(request: &str) -> Option<ServoUrl> {
diff --git a/ports/servo/glutin_app/window.rs b/ports/servo/glutin_app/window.rs
index 436f7518eee..2324ea37ab0 100644
--- a/ports/servo/glutin_app/window.rs
+++ b/ports/servo/glutin_app/window.rs
@@ -11,9 +11,9 @@ use gleam::gl;
 use glutin::{Api, ContextBuilder, GlContext, GlRequest, GlWindow};
 #[cfg(any(target_os = "linux", target_os = "macos"))]
 use osmesa_sys;
-use servo::compositing::compositor_thread::EventLoopWaker;
 use servo::compositing::windowing::{AnimationState, MouseWindowEvent, WindowEvent};
 use servo::compositing::windowing::{EmbedderCoordinates, WindowMethods};
+use servo::embedder_traits::EventLoopWaker;
 use servo::msg::constellation_msg::{Key, KeyState};
 use servo::script_traits::TouchEventType;
 use servo::servo_config::opts;