diff --git a/components/compositing/compositor.rs b/components/compositing/compositor.rs
index 145b57ef5d7..f5ef97f9f43 100644
--- a/components/compositing/compositor.rs
+++ b/components/compositing/compositor.rs
@@ -825,6 +825,13 @@ impl<Window: WindowMethods> IOCompositor<Window> {
                     warn!("Sending NewBrowser message to constellation failed ({}).", e);
                 }
             }
+
+            WindowEvent::SelectBrowser(ctx) => {
+                let msg = ConstellationMsg::SelectBrowser(ctx);
+                if let Err(e) = self.constellation_chan.send(msg) {
+                    warn!("Sending SelectBrowser message to constellation failed ({}).", e);
+                }
+            }
         }
     }
 
diff --git a/components/compositing/windowing.rs b/components/compositing/windowing.rs
index 7e044dfeb6c..cceaaf9fce8 100644
--- a/components/compositing/windowing.rs
+++ b/components/compositing/windowing.rs
@@ -73,6 +73,9 @@ pub enum WindowEvent {
     Reload(TopLevelBrowsingContextId),
     /// Create a new top level browsing context
     NewBrowser(ServoUrl, IpcSender<TopLevelBrowsingContextId>),
+    /// Make a top level browsing context visible, hiding the previous
+    /// visible one.
+    SelectBrowser(TopLevelBrowsingContextId),
 }
 
 impl Debug for WindowEvent {
@@ -96,6 +99,7 @@ impl Debug for WindowEvent {
             WindowEvent::ToggleWebRenderProfiler => write!(f, "ToggleWebRenderProfiler"),
             WindowEvent::Reload(..) => write!(f, "Reload"),
             WindowEvent::NewBrowser(..) => write!(f, "NewBrowser"),
+            WindowEvent::SelectBrowser(..) => write!(f, "SelectBrowser"),
         }
     }
 }
diff --git a/components/constellation/constellation.rs b/components/constellation/constellation.rs
index 5c849352c67..1685a32d8d2 100644
--- a/components/constellation/constellation.rs
+++ b/components/constellation/constellation.rs
@@ -174,6 +174,9 @@ pub struct Constellation<Message, LTF, STF> {
     /// constellation to send messages to the compositor thread.
     compositor_proxy: CompositorProxy,
 
+    /// The last frame tree sent to WebRender.
+    active_browser_id: Option<TopLevelBrowsingContextId>,
+
     /// Channels for the constellation to send messages to the public
     /// resource-related threads.  There are two groups of resource
     /// threads: one for public browsing, and one for private
@@ -527,6 +530,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                 network_listener_sender: network_listener_sender,
                 network_listener_receiver: network_listener_receiver,
                 compositor_proxy: state.compositor_proxy,
+                active_browser_id: None,
                 debugger_chan: state.debugger_chan,
                 devtools_chan: state.devtools_chan,
                 bluetooth_thread: state.bluetooth_thread,
@@ -963,6 +967,10 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
                 debug!("constellation got init load URL message");
                 self.handle_new_top_level_browsing_context(url, response_chan);
             }
+            // Send frame tree to WebRender. Make it visible.
+            FromCompositorMsg::SelectBrowser(top_level_browsing_context_id) => {
+                self.send_frame_tree(top_level_browsing_context_id);
+            }
             // Handle a forward or back request
             FromCompositorMsg::TraverseHistory(top_level_browsing_context_id, direction) => {
                 debug!("constellation got traverse history message from compositor");
@@ -2306,7 +2314,11 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         self.notify_history_changed(top_level_id);
 
         // Set paint permissions correctly for the compositor layers.
-        self.send_frame_tree(top_level_id);
+        if let Some(id) = self.active_browser_id {
+            if id == top_level_id {
+                self.send_frame_tree(top_level_id);
+            }
+        }
 
         // Update the owning iframe to point to the new pipeline id.
         // This makes things like contentDocument work correctly.
@@ -2465,7 +2477,11 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
         }
 
         // Build frame tree
-        self.send_frame_tree(change.top_level_browsing_context_id);
+        if let Some(id) = self.active_browser_id {
+            if id == change.top_level_browsing_context_id {
+                self.send_frame_tree(change.top_level_browsing_context_id );
+            }
+        }
     }
 
     fn handle_activate_document_msg(&mut self, pipeline_id: PipelineId) {
@@ -2902,6 +2918,7 @@ impl<Message, LTF, STF> Constellation<Message, LTF, STF>
     fn send_frame_tree(&mut self, top_level_browsing_context_id: TopLevelBrowsingContextId) {
         // This might be a mozbrowser iframe, so we need to climb the parent hierarchy,
         // even though it's a top-level browsing context.
+        self.active_browser_id = Some(top_level_browsing_context_id);
         let mut browsing_context_id = BrowsingContextId::from(top_level_browsing_context_id);
         let mut pipeline_id = match self.browsing_contexts.get(&browsing_context_id) {
             Some(browsing_context) => browsing_context.pipeline_id,
diff --git a/components/script_traits/lib.rs b/components/script_traits/lib.rs
index ec08b205c31..85122d35c3c 100644
--- a/components/script_traits/lib.rs
+++ b/components/script_traits/lib.rs
@@ -765,6 +765,8 @@ pub enum ConstellationMsg {
     WebVREvents(Vec<PipelineId>, Vec<WebVREvent>),
     /// Create a new top level browsing context.
     NewBrowser(ServoUrl, IpcSender<TopLevelBrowsingContextId>),
+    /// Make browser visible.
+    SelectBrowser(TopLevelBrowsingContextId),
 }
 
 /// Resources required by workerglobalscopes