Created attachment 178627 [details] glxgears resizing bug SUMMARY I have a strange behavior in glxgears and an app i made using SkiaSharp, which internally uses OpenGL. When I resize the window, the content covers it really slow instead of instantly. Since this isssue is also present in glxgears, I assume it’s not my code at fault, since this only started to happen after I upgraded to Plasma 6.3.0. Also, the app runs fine on Windows 11. STEPS TO REPRODUCE 1. Use Plasma 6.3.0 2. Launch glxgears from the terminal 3. Resize the window slowly or rapidly and see how it is redrawn OBSERVED RESULT The contents update really slowly and the drawing falls behind in pace compared to the resizing. It looks as if the surface can't keep up the pace of redrawing with the resizing. EXPECTED RESULT The contents update normally, (almost) instantly following the window's size, like the other apps SOFTWARE/OS VERSION Linux/KDE Plasma: Fedora KDE 41 (Wayland), Kernel version 6.12.13-200 KDE Plasma Version: 6.3.0 KDE Frameworks Version: 6.11.0 Qt Version: 6.8.2 ADDITIONAL INFORMATION I also attached a videos with glxgears being resized, to better observe the behavior
I can reproduce this in git-master
Update to this bug: It turns out it's even worse on Wayland when it happens! The videos were for X11, but on Wayland the behavior is that the entire window behaves like the drawing surface instead of being responsive and resize immediately following the user action. This means that if I slowly resize the window for several seconds, the resizing will still happen well after I release the mouse. Is there some progress on this bug or at least some clue on what part of the code is creating this? Thank you!
glxgears doesn't opt in into the _NET_WM_SYNC_REQUEST protocol, so it likely processes resize events one by one. I suggest to add support for _NET_WM_SYNC_REQUEST in your app. It'd reduce the number of ConfigureNotify events and it can also reduce the number of visual glitches during interactive resize.