diff --git a/layout/base/nsIPresShell.h b/layout/base/nsIPresShell.h
index 21a5aa57049..5f8efec8d75 100644
--- a/layout/base/nsIPresShell.h
+++ b/layout/base/nsIPresShell.h
@@ -127,8 +127,8 @@ typedef struct CapturingContentInfo {
 } CapturingContentInfo;
 
 #define NS_IPRESSHELL_IID     \
-{ 0x3c00dd85, 0xdc61, 0x4acc, \
-  { 0xa4, 0x0e, 0x9b, 0x91, 0xd2, 0xea, 0x4b, 0x27 } }
+{ 0x6736ae7e, 0x25f9, 0x4594, \
+  { 0xb5, 0x26, 0x49, 0x39, 0x17, 0x63, 0x2f, 0x94 } }
 
 // Constants for ScrollContentIntoView() function
 #define NS_PRESSHELL_SCROLL_TOP      0
@@ -630,26 +630,26 @@ public:
     * Interface to dispatch events via the presshell
     * @note The caller must have a strong reference to the PresShell.
     */
-  NS_IMETHOD HandleEventWithTarget(nsEvent* aEvent,
-                                   nsIFrame* aFrame,
-                                   nsIContent* aContent,
-                                   nsEventStatus* aStatus) = 0;
+  virtual NS_HIDDEN_(nsresult) HandleEventWithTarget(nsEvent* aEvent,
+                                                     nsIFrame* aFrame,
+                                                     nsIContent* aContent,
+                                                     nsEventStatus* aStatus) = 0;
 
   /**
    * Dispatch event to content only (NOT full processing)
    * @note The caller must have a strong reference to the PresShell.
    */
-  NS_IMETHOD HandleDOMEventWithTarget(nsIContent* aTargetContent,
-                                      nsEvent* aEvent,
-                                      nsEventStatus* aStatus) = 0;
+  virtual NS_HIDDEN_(nsresult) HandleDOMEventWithTarget(nsIContent* aTargetContent,
+                                                        nsEvent* aEvent,
+                                                        nsEventStatus* aStatus) = 0;
 
   /**
    * Dispatch event to content only (NOT full processing)
    * @note The caller must have a strong reference to the PresShell.
    */
-  NS_IMETHOD HandleDOMEventWithTarget(nsIContent* aTargetContent,
-                                      nsIDOMEvent* aEvent,
-                                      nsEventStatus* aStatus) = 0;
+  virtual NS_HIDDEN_(nsresult) HandleDOMEventWithTarget(nsIContent* aTargetContent,
+                                                        nsIDOMEvent* aEvent,
+                                                        nsEventStatus* aStatus) = 0;
 
   /**
     * Gets the current target event frame from the PresShell
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index cc5bf2a19eb..f5b2b3169d6 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -752,9 +752,9 @@ public:
   virtual nsresult AddOverrideStyleSheet(nsIStyleSheet *aSheet);
   virtual nsresult RemoveOverrideStyleSheet(nsIStyleSheet *aSheet);
 
-  NS_IMETHOD HandleEventWithTarget(nsEvent* aEvent, nsIFrame* aFrame,
-                                   nsIContent* aContent,
-                                   nsEventStatus* aStatus);
+  virtual NS_HIDDEN_(nsresult) HandleEventWithTarget(nsEvent* aEvent, nsIFrame* aFrame,
+                                                     nsIContent* aContent,
+                                                     nsEventStatus* aStatus);
   virtual NS_HIDDEN_(nsIFrame*) GetEventTargetFrame();
   virtual NS_HIDDEN_(already_AddRefed<nsIContent>) GetEventTargetContent(nsEvent* aEvent);
 
@@ -795,12 +795,12 @@ public:
   NS_IMETHOD HandleEvent(nsIView*        aView,
                          nsGUIEvent*     aEvent,
                          nsEventStatus*  aEventStatus);
-  NS_IMETHOD HandleDOMEventWithTarget(nsIContent* aTargetContent,
-                                      nsEvent* aEvent,
-                                      nsEventStatus* aStatus);
-  NS_IMETHOD HandleDOMEventWithTarget(nsIContent* aTargetContent,
-                                      nsIDOMEvent* aEvent,
-                                      nsEventStatus* aStatus);
+  virtual NS_HIDDEN_(nsresult) HandleDOMEventWithTarget(nsIContent* aTargetContent,
+                                                        nsEvent* aEvent,
+                                                        nsEventStatus* aStatus);
+  virtual NS_HIDDEN_(nsresult) HandleDOMEventWithTarget(nsIContent* aTargetContent,
+                                                        nsIDOMEvent* aEvent,
+                                                        nsEventStatus* aStatus);
   NS_IMETHOD ResizeReflow(nsIView *aView, nscoord aWidth, nscoord aHeight);
   NS_IMETHOD_(PRBool) IsVisible();
   NS_IMETHOD_(void) WillPaint();
@@ -6285,16 +6285,14 @@ PresShell::HandlePositionedEvent(nsIView*       aView,
   return rv;
 }
 
-NS_IMETHODIMP
+nsresult
 PresShell::HandleEventWithTarget(nsEvent* aEvent, nsIFrame* aFrame,
                                  nsIContent* aContent, nsEventStatus* aStatus)
 {
-  nsresult ret;
-
   PushCurrentEventInfo(aFrame, aContent);
-  ret = HandleEventInternal(aEvent, nsnull, aStatus);
+  nsresult rv = HandleEventInternal(aEvent, nsnull, aStatus);
   PopCurrentEventInfo();
-  return NS_OK;
+  return rv;
 }
 
 static inline PRBool
@@ -6466,10 +6464,12 @@ PresShell::HandleEventInternal(nsEvent* aEvent, nsIView *aView,
 
 // Dispatch event to content only (NOT full processing)
 // See also HandleEventWithTarget which does full event processing.
-NS_IMETHODIMP
+nsresult
 PresShell::HandleDOMEventWithTarget(nsIContent* aTargetContent, nsEvent* aEvent,
                                     nsEventStatus* aStatus)
 {
+  nsresult rv = NS_OK;
+
   PushCurrentEventInfo(nsnull, aTargetContent);
 
   // Bug 41013: Check if the event should be dispatched to content.
@@ -6481,29 +6481,31 @@ PresShell::HandleDOMEventWithTarget(nsIContent* aTargetContent, nsEvent* aEvent,
   if (container) {
 
     // Dispatch event to content
-    nsEventDispatcher::Dispatch(aTargetContent, mPresContext, aEvent, nsnull,
-                                aStatus);
+    rv = nsEventDispatcher::Dispatch(aTargetContent, mPresContext, aEvent, nsnull,
+                                     aStatus);
   }
 
   PopCurrentEventInfo();
-  return NS_OK;
+  return rv;
 }
 
 // See the method above.
-NS_IMETHODIMP
+nsresult
 PresShell::HandleDOMEventWithTarget(nsIContent* aTargetContent,
                                     nsIDOMEvent* aEvent,
                                     nsEventStatus* aStatus)
 {
+  nsresult rv = NS_OK;
+
   PushCurrentEventInfo(nsnull, aTargetContent);
   nsCOMPtr<nsISupports> container = mPresContext->GetContainer();
   if (container) {
-    nsEventDispatcher::DispatchDOMEvent(aTargetContent, nsnull, aEvent,
-                                        mPresContext, aStatus);
+    rv = nsEventDispatcher::DispatchDOMEvent(aTargetContent, nsnull, aEvent,
+                                             mPresContext, aStatus);
   }
 
   PopCurrentEventInfo();
-  return NS_OK;
+  return rv;
 }
 
 PRBool