diff --git a/browser/base/content/tabbrowser.xml b/browser/base/content/tabbrowser.xml
index efd287287807..0db907fcdf73 100644
--- a/browser/base/content/tabbrowser.xml
+++ b/browser/base/content/tabbrowser.xml
@@ -3229,7 +3229,8 @@
                                           addonInfo: aMessage.data.addonInfo };
               let popup = browser.ownerDocument.getElementById("contentAreaContextMenu");
               let event = gContextMenuContentData.event;
-              popup.openPopupAtScreen(event.screenX, event.screenY, true);
+              let pos = browser.mapScreenCoordinatesFromContent(event.screenX, event.screenY);
+              popup.openPopupAtScreen(pos.x, pos.y, true);
               break;
             }
             case "DOMWebNotificationClicked": {
diff --git a/dom/base/nsFrameLoader.cpp b/dom/base/nsFrameLoader.cpp
index 982ec2eaeb91..4ac6eb6bb11c 100644
--- a/dom/base/nsFrameLoader.cpp
+++ b/dom/base/nsFrameLoader.cpp
@@ -914,7 +914,8 @@ nsFrameLoader::ShowRemoteFrame(const nsIntSize& size,
 
     // Don't show remote iframe if we are waiting for the completion of reflow.
     if (!aFrame || !(aFrame->GetStateBits() & NS_FRAME_FIRST_REFLOW)) {
-      mRemoteBrowser->UpdateDimensions(dimensions, size);
+      nsIntPoint chromeDisp = aFrame->GetChromeDisplacement();
+      mRemoteBrowser->UpdateDimensions(dimensions, size, chromeDisp);
     }
   }
 
@@ -1959,7 +1960,8 @@ nsFrameLoader::UpdatePositionAndSize(nsSubDocumentFrame *aIFrame)
       nsIntSize size = aIFrame->GetSubdocumentSize();
       nsIntRect dimensions;
       NS_ENSURE_SUCCESS(GetWindowDimensions(dimensions), NS_ERROR_FAILURE);
-      mRemoteBrowser->UpdateDimensions(dimensions, size);
+      nsIntPoint chromeDisp = aIFrame->GetChromeDisplacement();
+      mRemoteBrowser->UpdateDimensions(dimensions, size, chromeDisp);
     }
     return NS_OK;
   }
diff --git a/dom/base/nsFrameLoader.h b/dom/base/nsFrameLoader.h
index 0e02528e77a1..54a0ec50e276 100644
--- a/dom/base/nsFrameLoader.h
+++ b/dom/base/nsFrameLoader.h
@@ -227,9 +227,6 @@ public:
   void ActivateUpdateHitRegion();
   void DeactivateUpdateHitRegion();
 
-  // Properly retrieves documentSize of any subdocument type.
-  nsresult GetWindowDimensions(nsIntRect& aRect);
-
 private:
 
   void SetOwnerContent(mozilla::dom::Element* aContent);
@@ -285,6 +282,9 @@ private:
   nsresult MaybeCreateDocShell();
   nsresult EnsureMessageManager();
 
+  // Properly retrieves documentSize of any subdocument type.
+  nsresult GetWindowDimensions(nsIntRect& aRect);
+
   // Updates the subdocument position and size. This gets called only
   // when we have our own in-process DocShell.
   void UpdateBaseWindowPositionAndSize(nsSubDocumentFrame *aIFrame);
diff --git a/dom/ipc/TabChild.cpp b/dom/ipc/TabChild.cpp
index 1953d339bfae..43e710551a92 100644
--- a/dom/ipc/TabChild.cpp
+++ b/dom/ipc/TabChild.cpp
@@ -2011,7 +2011,7 @@ TabChild::RecvUpdateDimensions(const nsIntRect& rect, const nsIntSize& size,
     ScreenIntSize oldScreenSize = mInnerSize;
     mInnerSize = ScreenIntSize::FromUnknownSize(
       gfx::IntSize(size.width, size.height));
-    mWidget->Resize(rect.x + chromeDisp.x, rect.y + chromeDisp.y, size.width, size.height,
+    mWidget->Resize(0, 0, size.width, size.height,
                     true);
 
     nsCOMPtr<nsIBaseWindow> baseWin = do_QueryInterface(WebNavigation());
diff --git a/dom/ipc/TabParent.cpp b/dom/ipc/TabParent.cpp
index fbda3eb2dde2..8169ebf4fdaf 100644
--- a/dom/ipc/TabParent.cpp
+++ b/dom/ipc/TabParent.cpp
@@ -80,7 +80,6 @@
 #include "nsICancelable.h"
 #include "gfxPrefs.h"
 #include "nsILoginManagerPrompter.h"
-#include "nsPIWindowRoot.h"
 #include <algorithm>
 
 using namespace mozilla::dom;
@@ -322,27 +321,7 @@ TabParent::RemoveTabParentFromTable(uint64_t aLayersId)
 void
 TabParent::SetOwnerElement(Element* aElement)
 {
-  // If we held previous content then unregister for its events.
-  if (mFrameElement && mFrameElement->OwnerDoc()->GetWindow()) {
-    nsCOMPtr<nsPIDOMWindow> window = mFrameElement->OwnerDoc()->GetWindow();
-    nsCOMPtr<EventTarget> eventTarget = window->GetTopWindowRoot();
-    if (eventTarget) {
-      eventTarget->RemoveEventListener(NS_LITERAL_STRING("MozUpdateWindowPos"),
-                                       this, false);
-    }
-  }
-
-  // Update to the new content, and register to listen for events from it.
   mFrameElement = aElement;
-  if (mFrameElement && mFrameElement->OwnerDoc()->GetWindow()) {
-    nsCOMPtr<nsPIDOMWindow> window = mFrameElement->OwnerDoc()->GetWindow();
-    nsCOMPtr<EventTarget> eventTarget = window->GetTopWindowRoot();
-    if (eventTarget) {
-      eventTarget->AddEventListener(NS_LITERAL_STRING("MozUpdateWindowPos"),
-                                    this, false, false);
-    }
-  }
-
   TryCacheDPIAndScale();
 }
 
@@ -378,8 +357,6 @@ TabParent::Destroy()
     return;
   }
 
-  SetOwnerElement(nullptr);
-
   // If this fails, it's most likely due to a content-process crash,
   // and auto-cleanup will kick in.  Otherwise, the child side will
   // destroy itself and send back __delete__().
@@ -904,40 +881,9 @@ TabParent::RecvSetDimensions(const uint32_t& aFlags,
   return false;
 }
 
-static nsIntPoint
-GetChromeDisplacement(nsFrameLoader *aFrameLoader)
-{
-  if (!aFrameLoader) {
-    return nsIntPoint();
-  }
-
-  // Calculate the displacement from the primary frame of the tab
-  // content to the top-level frame of the widget we are in.
-  nsIFrame* contentFrame = aFrameLoader->GetPrimaryFrameOfOwningContent();
-  if (!contentFrame) {
-    return nsIntPoint();
-  }
-
-  nsIFrame* nextFrame = nsLayoutUtils::GetCrossDocParentFrame(contentFrame);
-  if (!nextFrame) {
-    NS_WARNING("Couldn't find window chrome to calculate displacement to.");
-    return nsIntPoint();
-  }
-
-  nsIFrame* rootFrame = nextFrame;
-  while (nextFrame) {
-    rootFrame = nextFrame;
-    nextFrame = nsLayoutUtils::GetCrossDocParentFrame(rootFrame);
-  }
-
-  nsPoint offset = contentFrame->GetOffsetToCrossDoc(rootFrame);
-  int32_t appUnitsPerDevPixel = rootFrame->PresContext()->AppUnitsPerDevPixel();
-  return nsIntPoint((int)(offset.x/appUnitsPerDevPixel),
-                    (int)(offset.y/appUnitsPerDevPixel));
-}
-
 void
-TabParent::UpdateDimensions(const nsIntRect& rect, const nsIntSize& size)
+TabParent::UpdateDimensions(const nsIntRect& rect, const nsIntSize& size,
+                            const nsIntPoint& aChromeDisp)
 {
   if (mIsDestroyed) {
     return;
@@ -948,22 +894,12 @@ TabParent::UpdateDimensions(const nsIntRect& rect, const nsIntSize& size)
 
   if (!mUpdatedDimensions || mOrientation != orientation ||
       mDimensions != size || !mRect.IsEqualEdges(rect)) {
-    nsCOMPtr<nsIWidget> widget = GetWidget();
-    nsIntRect contentRect = rect;
-    if (widget) {
-      contentRect.x += widget->GetClientOffset().x;
-      contentRect.y += widget->GetClientOffset().y;
-    }
-
     mUpdatedDimensions = true;
-    mRect = contentRect;
+    mRect = rect;
     mDimensions = size;
     mOrientation = orientation;
 
-    nsRefPtr<nsFrameLoader> frameLoader = GetFrameLoader();
-    nsIntPoint chromeOffset = GetChromeDisplacement(frameLoader);
-
-    unused << SendUpdateDimensions(mRect, mDimensions, mOrientation, chromeOffset);
+    unused << SendUpdateDimensions(mRect, mDimensions, mOrientation, aChromeDisp);
   }
 }
 
@@ -2716,27 +2652,6 @@ TabParent::DeallocPPluginWidgetParent(mozilla::plugins::PPluginWidgetParent* aAc
   return true;
 }
 
-nsresult
-TabParent::HandleEvent(nsIDOMEvent* aEvent)
-{
-  nsAutoString eventType;
-  aEvent->GetType(eventType);
-
-  if (eventType.EqualsLiteral("MozUpdateWindowPos")) {
-    // This event is sent when the widget moved.  Therefore we only update
-    // the position.
-    nsRefPtr<nsFrameLoader> frameLoader = GetFrameLoader();
-    if (!frameLoader) {
-      return NS_OK;
-    }
-    nsIntRect windowDims;
-    NS_ENSURE_SUCCESS(frameLoader->GetWindowDimensions(windowDims), NS_ERROR_FAILURE);
-    UpdateDimensions(windowDims, mDimensions);
-    return NS_OK;
-  }
-  return NS_OK;
-}
-
 class FakeChannel MOZ_FINAL : public nsIChannel,
                               public nsIAuthPromptCallback,
                               public nsIInterfaceRequestor,
diff --git a/dom/ipc/TabParent.h b/dom/ipc/TabParent.h
index 366af9ec3575..3a172fd6645a 100644
--- a/dom/ipc/TabParent.h
+++ b/dom/ipc/TabParent.h
@@ -22,7 +22,6 @@
 #include "Units.h"
 #include "WritingModes.h"
 #include "js/TypeDecls.h"
-#include "nsIDOMEventListener.h"
 
 class nsFrameLoader;
 class nsIFrameLoader;
@@ -59,8 +58,7 @@ class nsIContentParent;
 class Element;
 struct StructuredCloneData;
 
-class TabParent : public PBrowserParent
-                , public nsIDOMEventListener
+class TabParent : public PBrowserParent 
                 , public nsITabParent 
                 , public nsIAuthPromptProvider
                 , public nsISecureBrowserUI
@@ -100,9 +98,6 @@ public:
         mBrowserDOMWindow = aBrowserDOMWindow;
     }
 
-    // nsIDOMEventListener interfaces 
-    NS_DECL_NSIDOMEVENTLISTENER
-
     already_AddRefed<nsILoadContext> GetLoadContext();
 
     nsIXULBrowserWindow* GetXULBrowserWindow();
@@ -246,7 +241,8 @@ public:
     // message-sending functions under a layer of indirection and
     // eating the return values
     void Show(const nsIntSize& size, bool aParentIsActive);
-    void UpdateDimensions(const nsIntRect& rect, const nsIntSize& size);
+    void UpdateDimensions(const nsIntRect& rect, const nsIntSize& size,
+                          const nsIntPoint& chromeDisp);
     void UpdateFrame(const layers::FrameMetrics& aFrameMetrics);
     void UIResolutionChanged();
     void AcknowledgeScrollUpdate(const ViewID& aScrollId, const uint32_t& aScrollGeneration);
diff --git a/dom/plugins/base/nsPluginInstanceOwner.cpp b/dom/plugins/base/nsPluginInstanceOwner.cpp
index 58d19381b309..8bdadc0f2d5e 100644
--- a/dom/plugins/base/nsPluginInstanceOwner.cpp
+++ b/dom/plugins/base/nsPluginInstanceOwner.cpp
@@ -789,6 +789,7 @@ NPBool nsPluginInstanceOwner::ConvertPointPuppet(PuppetWidget *widget,
   tabContentBounds.ScaleInverseRoundOut(scaleFactor);
   int32_t windowH = tabContentBounds.height + int(chromeSize.y);
 
+  // This is actually relative to window-chrome.
   nsPoint pluginPosition = AsNsPoint(pluginFrame->GetScreenRect().TopLeft());
 
   // Convert (sourceX, sourceY) to 'real' (not PuppetWidget) screen space.
@@ -798,8 +799,8 @@ NPBool nsPluginInstanceOwner::ConvertPointPuppet(PuppetWidget *widget,
   nsPoint screenPoint;
   switch (sourceSpace) {
     case NPCoordinateSpacePlugin:
-      screenPoint = sourcePoint + pluginPosition +
-        pluginFrame->GetContentRectRelativeToSelf().TopLeft() / nsPresContext::AppUnitsPerCSSPixel();
+      screenPoint = sourcePoint + pluginFrame->GetContentRectRelativeToSelf().TopLeft() +
+        chromeSize + pluginPosition + windowPosition;
       break;
     case NPCoordinateSpaceWindow:
       screenPoint = nsPoint(sourcePoint.x, windowH-sourcePoint.y) +
@@ -822,8 +823,8 @@ NPBool nsPluginInstanceOwner::ConvertPointPuppet(PuppetWidget *widget,
   nsPoint destPoint;
   switch (destSpace) {
     case NPCoordinateSpacePlugin:
-      destPoint = screenPoint - pluginPosition -
-        pluginFrame->GetContentRectRelativeToSelf().TopLeft() / nsPresContext::AppUnitsPerCSSPixel();
+      destPoint = screenPoint - pluginFrame->GetContentRectRelativeToSelf().TopLeft() -
+        chromeSize - pluginPosition - windowPosition;
       break;
     case NPCoordinateSpaceWindow:
       destPoint = screenPoint - windowPosition;
diff --git a/embedding/browser/nsDocShellTreeOwner.cpp b/embedding/browser/nsDocShellTreeOwner.cpp
index fc0c7f58255c..4787a2c2408a 100644
--- a/embedding/browser/nsDocShellTreeOwner.cpp
+++ b/embedding/browser/nsDocShellTreeOwner.cpp
@@ -1453,15 +1453,9 @@ ChromeTooltipListener::sTooltipCallback(nsITimer *aTimer,
       if (textFound) {
         nsString tipText(tooltipText);
         LayoutDeviceIntPoint screenDot = widget->WidgetToScreenOffset();
-        double scaleFactor = 1.0;
-        if (shell->GetPresContext()) {
-          scaleFactor = double(nsPresContext::AppUnitsPerCSSPixel())/
-          shell->GetPresContext()->DeviceContext()->AppUnitsPerDevPixelAtUnitFullZoom();
-        }
-        // ShowTooltip expects widget-relative position.
-        self->ShowTooltip(self->mMouseScreenX - screenDot.x / scaleFactor,
-          self->mMouseScreenY - screenDot.y / scaleFactor,
-          tipText);
+        self->ShowTooltip(self->mMouseScreenX - screenDot.x,
+                          self->mMouseScreenY - screenDot.y,
+                          tipText);
       }
     }
 
diff --git a/layout/generic/nsSubDocumentFrame.cpp b/layout/generic/nsSubDocumentFrame.cpp
index a470a66b952c..4a74295513a1 100644
--- a/layout/generic/nsSubDocumentFrame.cpp
+++ b/layout/generic/nsSubDocumentFrame.cpp
@@ -1274,3 +1274,24 @@ nsSubDocumentFrame::ObtainIntrinsicSizeFrame()
   }
   return nullptr;
 }
+
+nsIntPoint
+nsSubDocumentFrame::GetChromeDisplacement()
+{
+  nsIFrame* nextFrame = nsLayoutUtils::GetCrossDocParentFrame(this);
+  if (!nextFrame) {
+    NS_WARNING("Couldn't find window chrome to calculate displacement to.");
+    return nsIntPoint();
+  }
+
+  nsIFrame* rootFrame = nextFrame;
+  while (nextFrame) {
+    rootFrame = nextFrame;
+    nextFrame = nsLayoutUtils::GetCrossDocParentFrame(rootFrame);
+  }
+
+  nsPoint offset = GetOffsetToCrossDoc(rootFrame);
+  int32_t appUnitsPerDevPixel = rootFrame->PresContext()->AppUnitsPerDevPixel();
+  return nsIntPoint((int)(offset.x/appUnitsPerDevPixel),
+                    (int)(offset.y/appUnitsPerDevPixel));
+}
diff --git a/layout/generic/nsSubDocumentFrame.h b/layout/generic/nsSubDocumentFrame.h
index f409f3bd4759..788e4d8d9b63 100644
--- a/layout/generic/nsSubDocumentFrame.h
+++ b/layout/generic/nsSubDocumentFrame.h
@@ -127,6 +127,8 @@ public:
    */
   bool PassPointerEventsToChildren();
 
+  nsIntPoint GetChromeDisplacement();
+
 protected:
   friend class AsyncFrameInit;
 
diff --git a/toolkit/components/satchel/AutoCompleteE10S.jsm b/toolkit/components/satchel/AutoCompleteE10S.jsm
index 1e506fd97b27..3928b273dec2 100644
--- a/toolkit/components/satchel/AutoCompleteE10S.jsm
+++ b/toolkit/components/satchel/AutoCompleteE10S.jsm
@@ -81,8 +81,9 @@ this.AutoCompleteE10S = {
     this.popup.hidden = false;
     this.popup.setAttribute("width", rect.width);
 
-    this.x = rect.left;
-    this.y = rect.top + rect.height;
+    let {x, y} = this.browser.mapScreenCoordinatesFromContent(rect.left, rect.top + rect.height);
+    this.x = x;
+    this.y = y;
   },
 
   _showPopup: function(results) {
diff --git a/toolkit/content/widgets/browser.xml b/toolkit/content/widgets/browser.xml
index 4122681e1c7f..e42c917683e0 100644
--- a/toolkit/content/widgets/browser.xml
+++ b/toolkit/content/widgets/browser.xml
@@ -877,7 +877,8 @@
               if (!this.autoscrollEnabled) {
                 return false;
               }
-              this.startScroll(data.scrolldir, data.screenX, data.screenY);
+              let pos = this.mapScreenCoordinatesFromContent(data.screenX, data.screenY);
+              this.startScroll(data.scrolldir, pos.x, pos.y);
               return true;
             }
             case "Autoscroll:Cancel":
@@ -1058,6 +1059,25 @@
         </body>
       </method>
 
+      <!--
+        For out-of-process code, event.screen[XY] is relative to the
+        left/top of the content view. For in-process code,
+        event.screen[XY] is relative to the left/top of the screen. We
+        use this method to map screen coordinates received from a
+        (possibly out-of-process) <browser> element to coordinates
+        that are relative to the screen. This code handles the
+        in-process case, where we return the coordinates unchanged.
+      -->
+      <method name="mapScreenCoordinatesFromContent">
+        <parameter name="aScreenX"/>
+        <parameter name="aScreenY"/>
+        <body>
+        <![CDATA[
+          return { x: aScreenX, y: aScreenY };
+        ]]>
+        </body>
+      </method>
+
       <method name="swapDocShells">
         <parameter name="aOtherBrowser"/>
         <body>
diff --git a/toolkit/content/widgets/remote-browser.xml b/toolkit/content/widgets/remote-browser.xml
index b1fbb32a9455..019446689078 100644
--- a/toolkit/content/widgets/remote-browser.xml
+++ b/toolkit/content/widgets/remote-browser.xml
@@ -391,6 +391,27 @@
         ]]></body>
       </method>
 
+      <!--
+        For out-of-process code, event.screen[XY] is relative to the
+        left/top of the content view. For in-process code,
+        event.screen[XY] is relative to the left/top of the screen. We
+        use this method to map screen coordinates received from a
+        (possibly out-of-process) <browser> element to coordinates
+        that are relative to the screen. This code handles the
+        out-of-process case, where we need to translate by the screen
+        position of the <browser> element.
+      -->
+      <method name="mapScreenCoordinatesFromContent">
+        <parameter name="aScreenX"/>
+        <parameter name="aScreenY"/>
+        <body>
+        <![CDATA[
+          return { x: aScreenX + this.boxObject.screenX,
+                   y: aScreenY + this.boxObject.screenY };
+        ]]>
+        </body>
+      </method>
+
       <method name="enableDisableCommands">
         <parameter name="aAction"/>
         <parameter name="aEnabledLength"/>
diff --git a/toolkit/modules/SelectParentHelper.jsm b/toolkit/modules/SelectParentHelper.jsm
index 60a179fa0239..5d6b87425080 100644
--- a/toolkit/modules/SelectParentHelper.jsm
+++ b/toolkit/modules/SelectParentHelper.jsm
@@ -28,7 +28,8 @@ this.SelectParentHelper = {
     currentBrowser = browser;
     this._registerListeners(menulist.menupopup);
 
-    menulist.menupopup.openPopupAtScreen(rect.left, rect.top + rect.height);
+    let {x, y} = browser.mapScreenCoordinatesFromContent(rect.left, rect.top + rect.height);
+    menulist.menupopup.openPopupAtScreen(x, y);
     menulist.selectedItem.scrollIntoView();
   },
 
diff --git a/widget/PuppetWidget.cpp b/widget/PuppetWidget.cpp
index 54714b4a5e9a..acfe7001026a 100644
--- a/widget/PuppetWidget.cpp
+++ b/widget/PuppetWidget.cpp
@@ -965,13 +965,6 @@ PuppetWidget::GetWindowPosition()
   return nsIntPoint(winX, winY);
 }
 
-NS_METHOD
-PuppetWidget::GetScreenBounds(nsIntRect &aRect) {
-  aRect.MoveTo(LayoutDeviceIntPoint::ToUntyped(WidgetToScreenOffset()));
-  aRect.SizeTo(mBounds.Size());
-  return NS_OK;
-}
-
 PuppetScreen::PuppetScreen(void *nativeScreen)
 {
 }
diff --git a/widget/PuppetWidget.h b/widget/PuppetWidget.h
index 5c566a16c56a..f6f82b8f9465 100644
--- a/widget/PuppetWidget.h
+++ b/widget/PuppetWidget.h
@@ -78,7 +78,7 @@ public:
                                int32_t* aY) MOZ_OVERRIDE
   { *aX = kMaxDimension;  *aY = kMaxDimension;  return NS_OK; }
 
-  // Widget position is controlled by the parent process via TabChild.
+  // We're always at <0, 0>, and so ignore move requests.
   NS_IMETHOD Move(double aX, double aY) MOZ_OVERRIDE
   { return NS_OK; }
 
@@ -90,14 +90,8 @@ public:
                     double aWidth,
                     double aHeight,
                     bool   aRepaint) MOZ_OVERRIDE
-  {
-    if (mBounds.x != aX || mBounds.y != aY) {
-      NotifyWindowMoved(aX, aY);
-    }
-    mBounds.x = aX;
-    mBounds.y = aY;
-    return Resize(aWidth, aHeight, aRepaint);
-  }
+  // (we're always at <0, 0>)
+  { return Resize(aWidth, aHeight, aRepaint); }
 
   // XXX/cjones: copying gtk behavior here; unclear what disabling a
   // widget is supposed to entail
@@ -127,8 +121,9 @@ public:
   NS_IMETHOD SetTitle(const nsAString& aTitle) MOZ_OVERRIDE
   { return NS_ERROR_UNEXPECTED; }
   
+  // PuppetWidgets are always at <0, 0>.
   virtual mozilla::LayoutDeviceIntPoint WidgetToScreenOffset() MOZ_OVERRIDE
-  { return LayoutDeviceIntPoint::FromUntyped(GetWindowPosition() + GetChromeDimensions()); }
+  { return mozilla::LayoutDeviceIntPoint(0, 0); }
 
   void InitEvent(WidgetGUIEvent& aEvent, nsIntPoint* aPoint = nullptr);
 
@@ -201,8 +196,6 @@ public:
   // Get the screen position of the application window.
   nsIntPoint GetWindowPosition();
 
-  NS_IMETHOD GetScreenBounds(nsIntRect &aRect) MOZ_OVERRIDE;
-
   NS_IMETHOD StartPluginIME(const mozilla::WidgetKeyboardEvent& aKeyboardEvent,
                             int32_t aPanelX, int32_t aPanelY,
                             nsString& aCommitted) MOZ_OVERRIDE;
diff --git a/xpfe/appshell/nsWebShellWindow.cpp b/xpfe/appshell/nsWebShellWindow.cpp
index 4c6632f680ea..29dde6155d25 100644
--- a/xpfe/appshell/nsWebShellWindow.cpp
+++ b/xpfe/appshell/nsWebShellWindow.cpp
@@ -71,8 +71,6 @@
 #include "mozilla/DebugOnly.h"
 #include "mozilla/MouseEvents.h"
 
-#include "nsPIWindowRoot.h"
-
 #ifdef XP_MACOSX
 #include "nsINativeMenuService.h"
 #define USE_NATIVE_MENUS
@@ -259,15 +257,6 @@ nsWebShellWindow::WindowMoved(nsIWidget* aWidget, int32_t x, int32_t y)
     pm->AdjustPopupsOnWindowChange(window);
   }
 
-  // Notify all tabs that the widget moved.
-  if (mDocShell && mDocShell->GetWindow()) {
-    nsCOMPtr<EventTarget> eventTarget = mDocShell->GetWindow()->GetTopWindowRoot();
-    nsContentUtils::DispatchChromeEvent(mDocShell->GetDocument(),
-                                        eventTarget,
-                                        NS_LITERAL_STRING("MozUpdateWindowPos"),
-                                        false, false, nullptr);
-  }
-
   // Persist position, but not immediately, in case this OS is firing
   // repeated move events as the user drags the window
   SetPersistenceTimer(PAD_POSITION);