Created attachment 594175 [details] [diff] [review]
I often hit an assertion that mLastPaintEndTime is uninitialized in DispatchPendingEvents on Wine. While there may be a bug in Wine that causes different message sequence that is not observed on Windows, I don't see a reason to believe that it will be set in OnPaint before an attempt to access it, so AFAICT it may happen on Windows as well. The attached patch initializes mLastPaintEndTime in nsWindow constructor.
Thanks for the review.