Created attachment 139420 [details] Video recording of Kate flashing gray for 1 frame after closing a modal dialog SUMMARY If I open and close a dialog box in a Qt app, after the app's parent window animates from darkened to normal, it flashes dark gray briefly before appearing normal again. STEPS TO REPRODUCE 1. Ensure compositing is turned on. In the Desktop Effects settings page, ensure "Dialog Parent" is checked. 2. Open Kate or Okular (I think any Qt app). 3. Open the "Open" or "Configure" dialog (I think any modal dialog). I recommend dragging the dialog aside to see the main window better. 4. Click the X button in the dialog's title bar. OBSERVED RESULT The main Kate window fades from gray to white, then flashes gray for one frame before returning to white. (I'm using Breeze widgets with Breeze colors.) EXPECTED RESULT The flash of darkened gray does not happen. SOFTWARE/OS VERSIONS Operating System: Arch Linux KDE Plasma Version: 5.22.1 KDE Frameworks Version: 5.83.0 Qt Version: 5.15.2 Kernel Version: 5.12.10-zen1-1-zen (64-bit) Graphics Platform: X11 Processors: 12 × AMD Ryzen 5 5600X 6-Core Processor Memory: 15.6 GiB of RAM Graphics Processor: NVIDIA GeForce GT 730/PCIe/SSE2 ADDITIONAL INFORMATION I discovered this bug on an Arch Linux system on a Nvidia GT 730 with compositor set to OpenGL 2.0. I also reproduced it on a libvirt VM running neon-user-20210610-0944.iso, in XRender compositing mode (to make the animations run at a normal speed instead of as quickly as possible). I only tested in Okular's open/settings dialogs (since Kate was not installed). Slowing down KDE animations may or may not make the flash more evident. I think this is a recent bug that was not present a few weeks ago (5.21.90 was probably unaffected, 5.22.0 may have been unaffected).
I can reliably reproduce this on my machine with an AMD Radeon RX 570 running Manjaro and Mesa drivers in just about any app, GTK included. In addition, the entire screen flickers similarly when I close an Authentication Required PolicyKit dialog box. The flashing color appears to be black on my screen. I tried all available rendering backends (OpenGL 3.1, OpenGL 2.0, XRender) and latency options, but any combination of the two compositor settings would still produce the same behavior. For now, I've disabled the Dialog Parent and Dim Screen For Administrator Mode effects as "workarounds." SOFTWARE/OS VERSIONS Operating System: Manjaro Linux KDE Plasma Version: 5.22.1 KDE Frameworks Version: 5.83.0 Qt Version: 5.15.2 Kernel Version: 5.12.10-1-MANJARO (64-bit) Graphics Platform: X11 Processors: 12 × AMD Ryzen 5 1600 Six-Core Processor Memory: 15.6 GiB of RAM Graphics Processor: Radeon RX 570 Series
This may or may not be related to https://bugs.kde.org/show_bug.cgi?id=438458 (Yakuake turning blue during a closing animation, and remaining blue for a long period of time rather than 1 frame). (In reply to Timothy B from comment #1) > The flashing color appears to be black on my screen. In my video recording (taken using SimpleScreenRecorder git), I frame-stepped in mpv (using the . key) to the frame where the window was dimmed, and the frame looked gray, not black. Can you check on your machine?
(In reply to nyanpasu64 from comment #2) > In my video recording (taken using SimpleScreenRecorder git), I > frame-stepped in mpv (using the . key) to the frame where the window was > dimmed, and the frame looked gray, not black. Can you check on your machine? I recorded the effect with my phone camera in slow motion and found that the flash is actually dark gray, possibly the same color as the flash in the attached video. It actually appeared black to my eyes in real time as the effect was very brief.
*** This bug has been marked as a duplicate of bug 438368 ***