Bug 743975 tried to make nsWebBrowser::PaintWindow() override nsIWidgetListener::PaintWindow(), but the method-signatures are different, so they're different methods. This triggers this build warning: { Warning: -Woverloaded-virtual in /mozilla/../obj/dist/include/nsIWidgetListener.h: ‘virtual bool nsIWidgetListener::PaintWindow(nsIWidget*, nsIntRegion, bool, bool)’ was hidden ../../../dist/include/nsIWidgetListener.h:126:16: warning: ‘virtual bool nsIWidgetListener::PaintWindow(nsIWidget*, nsIntRegion, bool, bool)’ was hidden [-Woverloaded-virtual] Warning: -Woverloaded-virtual in /mozilla/embedding/browser/webBrowser/nsWebBrowser.h: by ‘virtual bool nsWebBrowser::PaintWindow(nsIWidget*, bool, nsIntRegion, bool)’ /mozilla/embedding/browser/webBrowser/nsWebBrowser.h:127:18: warning: by ‘virtual bool nsWebBrowser::PaintWindow(nsIWidget*, bool, nsIntRegion, bool)’ [-Woverloaded-virtual] } Note the subtly different method-signatures -- "bool" and "nsIntRegion" are inverted. This appears to have been broken ever since nsIWidgetListener.h was created, back in bug 743975. (FWIW, if we'd annotated nsWebBrowser::PaintWindow as MOZ_OVERRIDE, this would have been a build error and we would have caught this.)

Depending on how PaintWindow() is invoked, this could mean we're never actually exercising the intended nsWebBrowser::PaintWindow() impl.

Matt, I noticed you changed the signature in the base class even more just three days after this bug was entered. Was it in response to this, are you in the middle of fixing this issue?

Nope, I hadn't seen this bug at all.

Neil, can you explain?

I think it was just intended to override that function. So let's just fix it.

Comment on attachment 692089 [details] [diff] [review] patch >- virtual bool PaintWindow(nsIWidget* aWidget, bool isRequest, nsIntRegion aRegion, bool aWillSendDidPaint); >+ virtual bool PaintWindow(nsIWidget* aWidget, nsIntRegion aRegion, uint32_t aFlags); Use MOZ_OVERRIDE to prevent a future mistake.

(In reply to Masatoshi Kimura [:emk] from comment #6) > Use MOZ_OVERRIDE to prevent a future mistake. +1 (per end of comment 0) :)

Arguably we should be adding that to every widget listener on every function, but I'm not going to do that, so I'll just do it the once here.