diff --git a/content/base/src/nsImageLoadingContent.cpp b/content/base/src/nsImageLoadingContent.cpp
index 3a3f3a253e7..bc565bee3ab 100644
--- a/content/base/src/nsImageLoadingContent.cpp
+++ b/content/base/src/nsImageLoadingContent.cpp
@@ -159,10 +159,11 @@ nsImageLoadingContent::~nsImageLoadingContent()
  * imgIContainerObserver impl
  */
 NS_IMETHODIMP
-nsImageLoadingContent::FrameChanged(imgIContainer* aContainer,
+nsImageLoadingContent::FrameChanged(imgIRequest* aRequest,
+                                    imgIContainer* aContainer,
                                     const nsIntRect* aDirtyRect)
 {
-  LOOP_OVER_OBSERVERS(FrameChanged(aContainer, aDirtyRect));
+  LOOP_OVER_OBSERVERS(FrameChanged(aRequest, aContainer, aDirtyRect));
   return NS_OK;
 }
             
diff --git a/content/base/src/nsStubImageDecoderObserver.cpp b/content/base/src/nsStubImageDecoderObserver.cpp
index 74f8aeea16e..91bac8b3883 100644
--- a/content/base/src/nsStubImageDecoderObserver.cpp
+++ b/content/base/src/nsStubImageDecoderObserver.cpp
@@ -113,7 +113,8 @@ nsStubImageDecoderObserver::OnImageIsAnimated(imgIRequest *aRequest)
 }
 
 NS_IMETHODIMP
-nsStubImageDecoderObserver::FrameChanged(imgIContainer *aContainer,
+nsStubImageDecoderObserver::FrameChanged(imgIRequest* aRequest,
+                                         imgIContainer *aContainer,
                                          const nsIntRect *aDirtyRect)
 {
     return NS_OK;
diff --git a/content/svg/content/src/nsSVGFilters.cpp b/content/svg/content/src/nsSVGFilters.cpp
index 0516dcad245..1b7411fdcd3 100644
--- a/content/svg/content/src/nsSVGFilters.cpp
+++ b/content/svg/content/src/nsSVGFilters.cpp
@@ -5742,11 +5742,12 @@ nsSVGFEImageElement::OnStopDecode(imgIRequest *aRequest,
 }
 
 NS_IMETHODIMP
-nsSVGFEImageElement::FrameChanged(imgIContainer *aContainer,
+nsSVGFEImageElement::FrameChanged(imgIRequest* aRequest,
+                                  imgIContainer *aContainer,
                                   const nsIntRect *aDirtyRect)
 {
   nsresult rv =
-    nsImageLoadingContent::FrameChanged(aContainer, aDirtyRect);
+    nsImageLoadingContent::FrameChanged(aRequest, aContainer, aDirtyRect);
   Invalidate();
   return rv;
 }
diff --git a/content/svg/content/src/nsSVGFilters.h b/content/svg/content/src/nsSVGFilters.h
index c4f9e38cf8f..d72e861530b 100644
--- a/content/svg/content/src/nsSVGFilters.h
+++ b/content/svg/content/src/nsSVGFilters.h
@@ -298,7 +298,8 @@ public:
   NS_IMETHOD OnStopDecode(imgIRequest *aRequest, nsresult status,
                           const PRUnichar *statusArg);
   // imgIContainerObserver
-  NS_IMETHOD FrameChanged(imgIContainer *aContainer,
+  NS_IMETHOD FrameChanged(imgIRequest* aRequest,
+                          imgIContainer *aContainer,
                           const nsIntRect *aDirtyRect);
   // imgIContainerObserver
   NS_IMETHOD OnStartContainer(imgIRequest *aRequest,
diff --git a/image/public/imgIContainerObserver.idl b/image/public/imgIContainerObserver.idl
index 30f24d750fe..361019e67d5 100644
--- a/image/public/imgIContainerObserver.idl
+++ b/image/public/imgIContainerObserver.idl
@@ -44,6 +44,7 @@
 %}
 
 interface imgIContainer;
+interface imgIRequest;
 [ptr] native nsIntRect(nsIntRect);
 
 /**
@@ -52,9 +53,10 @@ interface imgIContainer;
  * @author Stuart Parmenter <pavlov@netscape.com>
  * @version 0.1
  */
-[scriptable, uuid(aa2068c1-6b91-4f52-8603-487b14ac5f04)]
+[scriptable, uuid(f01efdb3-4b20-4313-a636-a2aa01a4ef5d)]
 interface imgIContainerObserver : nsISupports
 {
-  [noscript] void frameChanged(in imgIContainer aContainer,
+  [noscript] void frameChanged(in imgIRequest aRequest,
+                               in imgIContainer aContainer,
                                [const] in nsIntRect aDirtyRect);
 };
diff --git a/image/public/imgIDecoderObserver.idl b/image/public/imgIDecoderObserver.idl
index bed7cf6fc41..b7724c2fbca 100644
--- a/image/public/imgIDecoderObserver.idl
+++ b/image/public/imgIDecoderObserver.idl
@@ -77,7 +77,7 @@ interface imgIContainer;
  * @version 0.1
  * @see imagelib2
  */
-[scriptable, uuid(2e5fa0c4-57f8-4d16-bda3-1daeba9caa34)]
+[scriptable, uuid(5ca71b89-1a2f-475f-881d-d76c1531c4c8)]
 interface imgIDecoderObserver : imgIContainerObserver
 {
   /**
diff --git a/image/src/RasterImage.cpp b/image/src/RasterImage.cpp
index beb7b336978..bf33f74bb50 100644
--- a/image/src/RasterImage.cpp
+++ b/image/src/RasterImage.cpp
@@ -480,7 +480,7 @@ RasterImage::RequestRefresh(const mozilla::TimeStamp& aTime)
       mFramesNotified++;
     #endif
 
-    observer->FrameChanged(this, &dirtyRect);
+    observer->FrameChanged(nsnull, this, &dirtyRect);
   }
 }
 
@@ -1423,7 +1423,7 @@ RasterImage::ResetAnimation()
   // Update display if we were animating before
   nsCOMPtr<imgIContainerObserver> observer(do_QueryReferent(mObserver));
   if (mAnimating && observer)
-    observer->FrameChanged(this, &(mAnim->firstFrameRefreshArea));
+    observer->FrameChanged(nsnull, this, &(mAnim->firstFrameRefreshArea));
 
   if (ShouldAnimate()) {
     StartAnimation();
diff --git a/image/src/VectorImage.cpp b/image/src/VectorImage.cpp
index 181300cb141..611840f7dca 100644
--- a/image/src/VectorImage.cpp
+++ b/image/src/VectorImage.cpp
@@ -699,7 +699,7 @@ VectorImage::OnStopRequest(nsIRequest* aRequest, nsISupports* aCtxt,
     // NOTE: This signals that width/height are available.
     observer->OnStartContainer(nsnull, this);
 
-    observer->FrameChanged(this, &nsIntRect::GetMaxSizedIntRect());
+    observer->FrameChanged(nsnull, this, &nsIntRect::GetMaxSizedIntRect());
     observer->OnStopFrame(nsnull, 0);
     observer->OnStopDecode(nsnull, NS_OK, nsnull);
   }
@@ -738,7 +738,7 @@ VectorImage::InvalidateObserver()
 
   nsCOMPtr<imgIContainerObserver> containerObs(do_QueryReferent(mObserver));
   if (containerObs) {
-    containerObs->FrameChanged(this, &nsIntRect::GetMaxSizedIntRect());
+    containerObs->FrameChanged(nsnull, this, &nsIntRect::GetMaxSizedIntRect());
   }
 
   nsCOMPtr<imgIDecoderObserver> decoderObs(do_QueryReferent(mObserver));
diff --git a/image/src/imgRequest.cpp b/image/src/imgRequest.cpp
index 3b0ee404f9d..ac84fc90688 100644
--- a/image/src/imgRequest.cpp
+++ b/image/src/imgRequest.cpp
@@ -514,8 +514,11 @@ imgRequest::RequestDecode()
 
 /** imgIContainerObserver methods **/
 
-/* [noscript] void frameChanged (in imgIContainer container, in nsIntRect dirtyRect); */
-NS_IMETHODIMP imgRequest::FrameChanged(imgIContainer *container,
+/* [noscript] void frameChanged (in imgIRequest request,
+                                 in imgIContainer container,
+                                 in nsIntRect dirtyRect); */
+NS_IMETHODIMP imgRequest::FrameChanged(imgIRequest *request,
+                                       imgIContainer *container,
                                        const nsIntRect *dirtyRect)
 {
   LOG_SCOPE(gImgLog, "imgRequest::FrameChanged");
diff --git a/image/src/imgRequestProxy.cpp b/image/src/imgRequestProxy.cpp
index dc23c1f7017..c36e9c8f804 100644
--- a/image/src/imgRequestProxy.cpp
+++ b/image/src/imgRequestProxy.cpp
@@ -614,7 +614,7 @@ void imgRequestProxy::FrameChanged(imgIContainer *container,
   if (mListener && !mCanceled) {
     // Hold a ref to the listener while we call it, just in case.
     nsCOMPtr<imgIDecoderObserver> kungFuDeathGrip(mListener);
-    mListener->FrameChanged(container, dirtyRect);
+    mListener->FrameChanged(this, container, dirtyRect);
   }
 }
 
diff --git a/layout/base/nsImageLoader.cpp b/layout/base/nsImageLoader.cpp
index 347b1738b5a..e90cc3e22c4 100644
--- a/layout/base/nsImageLoader.cpp
+++ b/layout/base/nsImageLoader.cpp
@@ -212,7 +212,8 @@ NS_IMETHODIMP nsImageLoader::OnStopRequest(imgIRequest *aRequest,
   return NS_OK;
 }
 
-NS_IMETHODIMP nsImageLoader::FrameChanged(imgIContainer *aContainer,
+NS_IMETHODIMP nsImageLoader::FrameChanged(imgIRequest *aRequest,
+                                          imgIContainer *aContainer,
                                           const nsIntRect *aDirtyRect)
 {
   if (!mFrame)
@@ -223,6 +224,8 @@ NS_IMETHODIMP nsImageLoader::FrameChanged(imgIContainer *aContainer,
     return NS_OK;
   }
 
+  NS_ASSERTION(aRequest == mRequest, "This is a neat trick.");
+
   nsRect r = aDirtyRect->IsEqualInterior(nsIntRect::GetMaxSizedIntRect()) ?
     nsRect(nsPoint(0, 0), mFrame->GetSize()) :
     aDirtyRect->ToAppUnits(nsPresContext::AppUnitsPerCSSPixel());
diff --git a/layout/base/nsImageLoader.h b/layout/base/nsImageLoader.h
index 0cdba70d7f1..85e27b223b2 100644
--- a/layout/base/nsImageLoader.h
+++ b/layout/base/nsImageLoader.h
@@ -90,7 +90,8 @@ public:
   // incrementally in nsImageFrame.cpp.
 
   // imgIContainerObserver (override nsStubImageDecoderObserver)
-  NS_IMETHOD FrameChanged(imgIContainer *aContainer,
+  NS_IMETHOD FrameChanged(imgIRequest *aRequest,
+                          imgIContainer *aContainer,
                           const nsIntRect *aDirtyRect);
 
   void Destroy();
diff --git a/layout/generic/nsBulletFrame.cpp b/layout/generic/nsBulletFrame.cpp
index 49120c65839..a5020a3eb6a 100644
--- a/layout/generic/nsBulletFrame.cpp
+++ b/layout/generic/nsBulletFrame.cpp
@@ -1547,7 +1547,8 @@ NS_IMETHODIMP nsBulletFrame::OnImageIsAnimated(imgIRequest* aRequest)
   return NS_OK;
 }
 
-NS_IMETHODIMP nsBulletFrame::FrameChanged(imgIContainer *aContainer,
+NS_IMETHODIMP nsBulletFrame::FrameChanged(imgIRequest *aRequest,
+                                          imgIContainer *aContainer,
                                           const nsIntRect *aDirtyRect)
 {
   // Invalidate the entire content area. Maybe it's not optimal but it's simple and
@@ -1700,11 +1701,12 @@ NS_IMETHODIMP nsBulletListener::OnImageIsAnimated(imgIRequest *aRequest)
   return mFrame->OnImageIsAnimated(aRequest);
 }
 
-NS_IMETHODIMP nsBulletListener::FrameChanged(imgIContainer *aContainer,
+NS_IMETHODIMP nsBulletListener::FrameChanged(imgIRequest *aRequest,
+                                             imgIContainer *aContainer,
                                              const nsIntRect *aDirtyRect)
 {
   if (!mFrame)
     return NS_OK;
 
-  return mFrame->FrameChanged(aContainer, aDirtyRect);
+  return mFrame->FrameChanged(aRequest, aContainer, aDirtyRect);
 }
diff --git a/layout/generic/nsBulletFrame.h b/layout/generic/nsBulletFrame.h
index e7142da4334..7ab909d62e3 100644
--- a/layout/generic/nsBulletFrame.h
+++ b/layout/generic/nsBulletFrame.h
@@ -68,7 +68,8 @@ public:
   NS_IMETHOD OnImageIsAnimated(imgIRequest *aRequest);
 
   // imgIContainerObserver (override nsStubImageDecoderObserver)
-  NS_IMETHOD FrameChanged(imgIContainer *aContainer,
+  NS_IMETHOD FrameChanged(imgIRequest *aRequest,
+                          imgIContainer *aContainer,
                           const nsIntRect *dirtyRect);
 
   void SetFrame(nsBulletFrame *frame) { mFrame = frame; }
@@ -122,7 +123,8 @@ public:
                           nsresult aStatus,
                           const PRUnichar *aStatusArg);
   NS_IMETHOD OnImageIsAnimated(imgIRequest *aRequest);
-  NS_IMETHOD FrameChanged(imgIContainer *aContainer,
+  NS_IMETHOD FrameChanged(imgIRequest *aRequest,
+                          imgIContainer *aContainer,
                           const nsIntRect *aDirtyRect);
 
   /* get list item text, without '.' */
diff --git a/layout/generic/nsImageFrame.cpp b/layout/generic/nsImageFrame.cpp
index ca5da70dc3e..1aa47613f8d 100644
--- a/layout/generic/nsImageFrame.cpp
+++ b/layout/generic/nsImageFrame.cpp
@@ -682,7 +682,8 @@ nsImageFrame::OnStopDecode(imgIRequest *aRequest,
 }
 
 nsresult
-nsImageFrame::FrameChanged(imgIContainer *aContainer,
+nsImageFrame::FrameChanged(imgIRequest *aRequest,
+                           imgIContainer *aContainer,
                            const nsIntRect *aDirtyRect)
 {
   if (!GetStyleVisibility()->IsVisible()) {
@@ -1988,7 +1989,8 @@ nsImageFrame::IconLoad::OnDiscard(imgIRequest *aRequest)
 }
 
 NS_IMETHODIMP
-nsImageFrame::IconLoad::FrameChanged(imgIContainer *aContainer,
+nsImageFrame::IconLoad::FrameChanged(imgIRequest *aRequest,
+                                     imgIContainer *aContainer,
                                      const nsIntRect *aDirtyRect)
 {
   nsTObserverArray<nsImageFrame*>::ForwardIterator iter(mIconObservers);
@@ -2043,13 +2045,14 @@ NS_IMETHODIMP nsImageListener::OnStopDecode(imgIRequest *aRequest,
   return mFrame->OnStopDecode(aRequest, status, statusArg);
 }
 
-NS_IMETHODIMP nsImageListener::FrameChanged(imgIContainer *aContainer,
+NS_IMETHODIMP nsImageListener::FrameChanged(imgIRequest *aRequest,
+                                            imgIContainer *aContainer,
                                             const nsIntRect *aDirtyRect)
 {
   if (!mFrame)
     return NS_ERROR_FAILURE;
 
-  return mFrame->FrameChanged(aContainer, aDirtyRect);
+  return mFrame->FrameChanged(aRequest, aContainer, aDirtyRect);
 }
 
 static bool
diff --git a/layout/generic/nsImageFrame.h b/layout/generic/nsImageFrame.h
index b6bc5c63e79..caba3ba0501 100644
--- a/layout/generic/nsImageFrame.h
+++ b/layout/generic/nsImageFrame.h
@@ -85,7 +85,8 @@ public:
   NS_IMETHOD OnStopDecode(imgIRequest *aRequest, nsresult status,
                           const PRUnichar *statusArg);
   // imgIContainerObserver (override nsStubImageDecoderObserver)
-  NS_IMETHOD FrameChanged(imgIContainer *aContainer,
+  NS_IMETHOD FrameChanged(imgIRequest *aRequest,
+                          imgIContainer *aContainer,
                           const nsIntRect *dirtyRect);
 
   void SetFrame(nsImageFrame *frame) { mFrame = frame; }
@@ -237,7 +238,8 @@ protected:
   nsresult OnStopDecode(imgIRequest *aRequest,
                         nsresult aStatus,
                         const PRUnichar *aStatusArg);
-  nsresult FrameChanged(imgIContainer *aContainer,
+  nsresult FrameChanged(imgIRequest *aRequest,
+                        imgIContainer *aContainer,
                         const nsIntRect *aDirtyRect);
 
 private:
diff --git a/layout/svg/base/src/nsSVGImageFrame.cpp b/layout/svg/base/src/nsSVGImageFrame.cpp
index 998b01fbcce..e42b5b836c0 100644
--- a/layout/svg/base/src/nsSVGImageFrame.cpp
+++ b/layout/svg/base/src/nsSVGImageFrame.cpp
@@ -62,7 +62,8 @@ public:
   NS_IMETHOD OnStopDecode(imgIRequest *aRequest, nsresult status,
                           const PRUnichar *statusArg);
   // imgIContainerObserver (override nsStubImageDecoderObserver)
-  NS_IMETHOD FrameChanged(imgIContainer *aContainer,
+  NS_IMETHOD FrameChanged(imgIRequest *aRequest,
+                          imgIContainer *aContainer,
                           const nsIntRect *aDirtyRect);
   // imgIContainerObserver (override nsStubImageDecoderObserver)
   NS_IMETHOD OnStartContainer(imgIRequest *aRequest,
@@ -555,7 +556,8 @@ NS_IMETHODIMP nsSVGImageListener::OnStopDecode(imgIRequest *aRequest,
   return NS_OK;
 }
 
-NS_IMETHODIMP nsSVGImageListener::FrameChanged(imgIContainer *aContainer,
+NS_IMETHODIMP nsSVGImageListener::FrameChanged(imgIRequest *aRequest,
+                                               imgIContainer *aContainer,
                                                const nsIntRect *aDirtyRect)
 {
   if (!mFrame)
diff --git a/layout/xul/base/src/nsImageBoxFrame.cpp b/layout/xul/base/src/nsImageBoxFrame.cpp
index ca07631f137..c03af4042d8 100644
--- a/layout/xul/base/src/nsImageBoxFrame.cpp
+++ b/layout/xul/base/src/nsImageBoxFrame.cpp
@@ -626,7 +626,8 @@ NS_IMETHODIMP nsImageBoxFrame::OnImageIsAnimated(imgIRequest *aRequest)
   return NS_OK;
 }
 
-NS_IMETHODIMP nsImageBoxFrame::FrameChanged(imgIContainer *aContainer,
+NS_IMETHODIMP nsImageBoxFrame::FrameChanged(imgIRequest *aRequest,
+                                            imgIContainer *aContainer,
                                             const nsIntRect *aDirtyRect)
 {
   nsBoxLayoutState state(PresContext());
@@ -681,12 +682,13 @@ NS_IMETHODIMP nsImageBoxListener::OnImageIsAnimated(imgIRequest* aRequest)
   return mFrame->OnImageIsAnimated(aRequest);
 }
 
-NS_IMETHODIMP nsImageBoxListener::FrameChanged(imgIContainer *aContainer,
+NS_IMETHODIMP nsImageBoxListener::FrameChanged(imgIRequest *aRequest,
+                                               imgIContainer *aContainer,
                                                const nsIntRect *aDirtyRect)
 {
   if (!mFrame)
     return NS_ERROR_FAILURE;
 
-  return mFrame->FrameChanged(aContainer, aDirtyRect);
+  return mFrame->FrameChanged(aRequest, aContainer, aDirtyRect);
 }
 
diff --git a/layout/xul/base/src/nsImageBoxFrame.h b/layout/xul/base/src/nsImageBoxFrame.h
index 720094af676..b7287f3fae0 100644
--- a/layout/xul/base/src/nsImageBoxFrame.h
+++ b/layout/xul/base/src/nsImageBoxFrame.h
@@ -61,7 +61,8 @@ public:
   NS_IMETHOD OnImageIsAnimated(imgIRequest* aRequest);
 
   // imgIContainerObserver (override nsStubImageDecoderObserver)
-  NS_IMETHOD FrameChanged(imgIContainer *aContainer,
+  NS_IMETHOD FrameChanged(imgIRequest *aRequest,
+                          imgIContainer *aContainer,
                           const nsIntRect *aDirtyRect);
 
   void SetFrame(nsImageBoxFrame *frame) { mFrame = frame; }
@@ -126,7 +127,8 @@ public:
                           const PRUnichar *statusArg);
   NS_IMETHOD OnImageIsAnimated(imgIRequest* aRequest);
 
-  NS_IMETHOD FrameChanged(imgIContainer *aContainer,
+  NS_IMETHOD FrameChanged(imgIRequest *aRequest,
+                          imgIContainer *aContainer,
                           const nsIntRect *aDirtyRect);
 
   virtual ~nsImageBoxFrame();
diff --git a/layout/xul/base/src/tree/src/nsTreeImageListener.cpp b/layout/xul/base/src/tree/src/nsTreeImageListener.cpp
index 3155f5d9224..39356406918 100644
--- a/layout/xul/base/src/tree/src/nsTreeImageListener.cpp
+++ b/layout/xul/base/src/tree/src/nsTreeImageListener.cpp
@@ -84,7 +84,8 @@ NS_IMETHODIMP nsTreeImageListener::OnDataAvailable(imgIRequest *aRequest,
   return NS_OK;
 }
 
-NS_IMETHODIMP nsTreeImageListener::FrameChanged(imgIContainer *aContainer,
+NS_IMETHODIMP nsTreeImageListener::FrameChanged(imgIRequest *aRequest,
+                                                imgIContainer *aContainer,
                                                 const nsIntRect *aDirtyRect)
 {
   Invalidate();
diff --git a/layout/xul/base/src/tree/src/nsTreeImageListener.h b/layout/xul/base/src/tree/src/nsTreeImageListener.h
index e0beba4d915..84264950fb1 100644
--- a/layout/xul/base/src/tree/src/nsTreeImageListener.h
+++ b/layout/xul/base/src/tree/src/nsTreeImageListener.h
@@ -60,7 +60,8 @@ public:
   NS_IMETHOD OnDataAvailable(imgIRequest *aRequest, bool aCurrentFrame,
                              const nsIntRect *aRect);
   // imgIContainerObserver (override nsStubImageDecoderObserver)
-  NS_IMETHOD FrameChanged(imgIContainer *aContainer,
+  NS_IMETHOD FrameChanged(imgIRequest *aRequest,
+                          imgIContainer *aContainer,
                           const nsIntRect *aDirtyRect);
 
   NS_IMETHOD ClearFrame();
diff --git a/toolkit/system/gnome/nsAlertsIconListener.cpp b/toolkit/system/gnome/nsAlertsIconListener.cpp
index 8cf8c575d16..4bc64e072f6 100644
--- a/toolkit/system/gnome/nsAlertsIconListener.cpp
+++ b/toolkit/system/gnome/nsAlertsIconListener.cpp
@@ -144,7 +144,8 @@ nsAlertsIconListener::OnStopDecode(imgIRequest* aRequest,
 }
 
 NS_IMETHODIMP
-nsAlertsIconListener::FrameChanged(imgIContainer* aContainer,
+nsAlertsIconListener::FrameChanged(imgIRequest* aRequest, 
+                                   imgIContainer* aContainer,
                                    const nsIntRect* aDirtyRect)
 {
   return NS_OK;
diff --git a/widget/cocoa/nsMenuItemIconX.mm b/widget/cocoa/nsMenuItemIconX.mm
index 13f866f2232..9505ea25da5 100644
--- a/widget/cocoa/nsMenuItemIconX.mm
+++ b/widget/cocoa/nsMenuItemIconX.mm
@@ -358,7 +358,8 @@ nsMenuItemIconX::LoadIcon(nsIURI* aIconURI)
 //
 
 NS_IMETHODIMP
-nsMenuItemIconX::FrameChanged(imgIContainer*   aContainer,
+nsMenuItemIconX::FrameChanged(imgIRequest* aRequest,
+                              imgIContainer*   aContainer,
                               const nsIntRect* aDirtyRect)
 {
   return NS_OK;