Created attachment 125354 [details] Opening Discover SUMMARY If a window is set to visible before it's been drawn to it is displayed with contents from a dirty buffer (in my case I see a copy of of what's seen in the screen). If this is only fixable by each application developer, then at least KDE apps should not show the issue. STEPS TO REPRODUCE 1. Start a program like Discover or LibreOffice OBSERVED RESULT A window frame is shown containing a static copy of what was in the screen before starting the application EXPECTED RESULT Window should only be visible when it's fully drawn, not with dirty contents. If this is not possible, at least it should show blank contents. SOFTWARE/OS VERSIONS Operating System: Kubuntu 19.10 KDE Plasma Version: 5.16.5 KDE Frameworks Version: 5.62.0 Qt Version: 5.12.4 ADDITIONAL INFORMATION Kernel Version: 5.3.0-26-lowlatency OS Type: 64-bit Processors: 8 × Intel® Core™ i7-3770K CPU @ 3.50GHz GPU Driver: NVIDIA Driver 430.50 Memory: 15.6 GiB of RAM
rip Neil Peart :( duplicate of bug 409262 ?
Discover exhibits this behavior, yes (I will build latest discover to check if this behavior is fixed there), but I think kwin shouldn't let this happen, it would be much nicer if at least it blanked the window contents when a new one is created, since there are many apps that show this issue
I have had this happen for a while also, and no it wasn't fixed in 5.18 as 409262 suggested may have happened. SOFTWARE/OS VERSIONS Operating System: Arch linux KDE Plasma Version: 5.21.1 KDE Frameworks Version: 5.79.0 Qt Version: 5.15.2 ADDITIONAL INFORMATION Kernel Version: 5.11.2-arch1-1 #1 SMP PREEMPT OS Type: 64-bit Processor: AMD Ryzen 3700x GPU: NVIDIA GeForce GTX 660 GPU Driver: NVIDIA Driver 460.56 Memory: 32 GiB of RAM
On X11, kwin uses sync counters to prevent cases like these. It seems like Discover updates the sync counter before actually rendering anything.
This bug was reported against an outdated version of KWin. We have made many changes since the. If the issue persists in newer versions can you reopen the bug report updating the version number.