Created attachment 166388 [details] Firefox persistent example SUMMARY When scaling is enabled (tested at 115% and 125%), some apps in some sizes experience artifacts at various borders. STEPS TO REPRODUCE 1. Enable scaling 2. Try to play around with window size OBSERVED RESULT Firefox shows clear black line on the right at some size. You tube shows shimmering lines on both sides at some size close to the native video width. Chrome shows remaining of the cursor outline at the bottom when maximized. EXPECTED RESULT No artifacts present, like with no scaling applied. SOFTWARE/OS VERSIONS Operating System: Fedora Linux 40 KDE Plasma Version: 6.0.0 KDE Frameworks Version: 6.0.0 Qt Version: 6.6.2 Kernel Version: 6.8.0-0.rc6.49.fc40.x86_64 (64-bit) Graphics Platform: Wayland Processors: 24 × AMD Ryzen 9 5900X 12-Core Processor Memory: 31.3 GiB of RAM Graphics Processor: AMD Radeon RX 7900 XTX Manufacturer: Micro-Star International Co., Ltd. Product Name: MS-7C84 System Version: 1.0 ADDITIONAL INFORMATION
Created attachment 166389 [details] Chrome bottom artifacts
So there are a couple of different issues involved here. The black line against the orange window is an app bug, as it's using client-side decorations so KWin isn't involved with it. Try switching to server-side decorations and see if it goes away. The static-looking line at the bottom of the screen is a KWin issue though; pretty sure it's bug 459373. If it goes away if you force Chromium into native Wayland mode, that's it.
(In reply to Nate Graham from comment #2) > So there are a couple of different issues involved here. The black line > against the orange window is an app bug, as it's using client-side > decorations so KWin isn't involved with it. Try switching to server-side > decorations and see if it goes away. The static-looking line at the bottom > of the screen is a KWin issue though; pretty sure it's bug 459373. If it > goes away if you force Chromium into native Wayland mode, that's it. So, for the Chrome, indeed, I've forced Chrome and Electron apps to use wayland and I cannot reproduce it anymore. For the firefox, it seems to be reproducible at 115% scaling, but not at 125%, or at least it's much harder to find that size with issue on 125%. The whole scaling thing is causing very weird behavior that's very difficult to reproduce, because it's changing all the time :(
Ok, let's mark this as a duplicate of Bug 459373, then. It's always changing because we're actively trying to improve fractional scaling! :) I'm daily-driving a dual-screen fractional scaling setup myself FWIW, so I feel the pain. I'm trying to use that pain to get the issues fixed faster! *** This bug has been marked as a duplicate of bug 459373 ***