Null out weak pointers when they become invalid. b=479749 r=josh sr=roc

widget/src/cocoa/nsChildView.mm

@@ -736,7 +736,6 @@ NS_IMETHODIMP nsChildView::Destroy()
 
   [mView widgetDestroyed];
 
-  nsBaseWidget::OnDestroy();
   nsBaseWidget::Destroy();
 
   ReportDestroyEvent(); 
@@ -744,6 +743,8 @@ NS_IMETHODIMP nsChildView::Destroy()
 
   TearDownView();
 
+  nsBaseWidget::OnDestroy();
+
   return NS_OK;
 
   NS_OBJC_END_TRY_ABORT_BLOCK_NSRESULT;
@@ -2942,7 +2943,7 @@ NSEvent* gLastDragEvent = nil;
 static const PRInt32 sShadowInvalidationInterval = 100;
 - (void)maybeInvalidateShadow
 {
-  if ([mWindow isOpaque] || ![mWindow hasShadow])
+  if (!mWindow || [mWindow isOpaque] || ![mWindow hasShadow])
     return;
 
   PRIntervalTime now = PR_IntervalNow();
@@ -2963,7 +2964,7 @@ static const PRInt32 sShadowInvalidationInterval = 100;
 
 - (void)invalidateShadow
 {
-  if (!mNeedsShadowInvalidation)
+  if (!mWindow || !mNeedsShadowInvalidation)
     return;
   [mWindow invalidateShadow];
   mNeedsShadowInvalidation = NO;
@@ -3659,6 +3660,9 @@ static nsEventStatus SendGeckoMouseEnterOrExitEvent(PRBool isTrusted,
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
 
+  if (!mWindow)
+    return;
+
   // Work around an Apple bug that causes the OS to continue sending
   // mouseMoved events to a window for a while after it's been miniaturized.
   // This may be related to a similar problem with popup windows (bmo bug
@@ -4173,10 +4177,13 @@ static nsEventStatus SendGeckoMouseEnterOrExitEvent(PRBool isTrusted,
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK_NIL;
 
+  if (!mWindow)
+    return nil;
+
   WindowDataMap* windowMap = [WindowDataMap sharedWindowDataMap];
 
   TopLevelWindowData* windowData = [windowMap dataForWindow:mWindow];
-  if (mWindow && !windowData)
+  if (!windowData)
   {
     windowData = [[TopLevelWindowData alloc] initWithWindow:mWindow];
     [windowMap setData:windowData forWindow:mWindow]; // takes ownership

widget/src/cocoa/nsCocoaWindow.mm

@@ -118,6 +118,25 @@ nsCocoaWindow::nsCocoaWindow()
 }
 
 
+// Under unusual circumstances, an nsCocoaWindow object can be destroyed
+// before the nsChildView objects it contains are destroyed.  But this will
+// invalidate the (weak) mWindow variable in these nsChildView objects
+// before their own destructors have been called.  So we need to null-out
+// this variable in our nsChildView objects as we're destroyed.  This helps
+// resolve bmo bug 479749.
+static void TellNativeViewsGoodbye(NSView *aNativeView)
+{
+  if (!aNativeView)
+    return;
+  if ([aNativeView respondsToSelector:@selector(setNativeWindow:)])
+    [(NSView<mozView>*)aNativeView setNativeWindow:nil];
+  NSArray *immediateSubviews = [aNativeView subviews];
+  int count = [immediateSubviews count];
+  for (int i = 0; i < count; ++i)
+    TellNativeViewsGoodbye((NSView *)[immediateSubviews objectAtIndex:i]);
+}
+
+
 nsCocoaWindow::~nsCocoaWindow()
 {
   NS_OBJC_BEGIN_TRY_ABORT_BLOCK;
@@ -128,13 +147,16 @@ nsCocoaWindow::~nsCocoaWindow()
     childWindow->mParent = nsnull;
   }
 
-  if (mWindow && mWindowMadeHere) {
+  if (mWindow) {
+    TellNativeViewsGoodbye([mWindow contentView]);
+    if (mWindowMadeHere) {
       // we want to unhook the delegate here because we don't want events
       // sent to it after this object has been destroyed
       [mWindow setDelegate:nil];
       [mWindow autorelease];
       [mDelegate autorelease];
     }
+  }
 
   NS_IF_RELEASE(mPopupContentView);
 
@@ -429,8 +451,8 @@ NS_IMETHODIMP nsCocoaWindow::Destroy()
   if (mPopupContentView)
     mPopupContentView->Destroy();
 
-  nsBaseWidget::OnDestroy();
   nsBaseWidget::Destroy();
+  nsBaseWidget::OnDestroy();
 
   return NS_OK;
 }

widget/src/xpwidgets/nsBaseWidget.cpp

@@ -256,6 +256,10 @@ NS_METHOD nsBaseWidget::Destroy()
   // Just in case our parent is the only ref to us
   nsCOMPtr<nsIWidget> kungFuDeathGrip(this);
   
+  // Clear the device context's mWidget field -- otherwise it may get accessed
+  // after it's been deleted.  See bug 479749.
+  if (mContext)
+    mContext->Init(nsnull);
   // disconnect from the parent
   nsIWidget *parent = GetParent();
   if (parent) {