Created attachment 115977 [details] the bug in action SUMMARY Windows exhibit a flash (short flicker) when closed and the Scale or Glide desktop effect is turned on. STEPS TO REPRODUCE 1. Turn on Glide or Scale in System Settings under Desktop Effects 2. Load a busy program (for my purposes it was Audacity, after loading and playing a random audio file). This bug is not always reproducible, may not even occur with Audacity in particular, is not specific to GTK or Qt, and does *not* occur in Wayland. 3. Close the window. OBSERVED RESULT Window renders desktop effect (Slide or Glide) properly and closes, then the window is reopened for a split second, and its contents emit a white flash before disappearing, see included attachment. EXPECTED RESULT Window renders desktop effect (Slide or Glide) properly and closes. SOFTWARE VERSIONS KDE Plasma Version: 5.14.2 KDE Frameworks Version: 5.51.0 Qt Version: 5.11.2 ADDITIONAL INFORMATION Appeared in 5.14.0, still present as of 5.14.2.
The cause for that is the Dialog Parent effect. It's been fixed in 5.15. We can't backport the fix to 5.14.x because the fix is quite big and we need more testing. But for now, you could disable the Dialog Parent effect and when 5.15 is released turn it on back.
(In reply to Vlad Zagorodniy from comment #1) > The cause for that is the Dialog Parent effect. It's been fixed in 5.15. We > can't backport the fix to 5.14.x because the fix is quite big and we need > more testing. > > But for now, you could disable the Dialog Parent effect and when 5.15 is > released turn it on back. nice!