Created attachment 172177 [details] System tray popup with dark icons SUMMARY I use Plasma 6 with Dark Breeze theme and the Oxygen icon set. Some icons in the System tray popup are missing in Oxygen. They are substituted by Breeze icons in dark variants, thus they're invisible on dark background. STEPS TO REPRODUCE 1. Use Breeze Twilight global motive. 2. Use Oxygen icon set. 3. Click on System tray to "Show hidden icons". OBSERVED RESULT Missing Oxygen icons are substituted by Breeze Dark variant. You can't see them. EXPECTED RESULT All icons should be visible. Missing Oxygen icons should be substituted by Breeze (light) variant. SOFTWARE/OS VERSIONS Operating System: KDE neon 6.0 KDE Plasma Version: 6.1.3 KDE Frameworks Version: 6.4.0 Qt Version: 6.7.0 Kernel Version: 6.5.0-44-generic (64-bit) Graphics Platform: X11 Processors: 16 × AMD Ryzen 7 5700X 8-Core Processor Memory: 31.3 GiB of RAM Graphics Processor: AMD Radeon RX 580 Series Manufacturer: Gigabyte Technology Co., Ltd. Product Name: B450 AORUS PRO
Created attachment 172178 [details] System tray settings with all icons You can see all possible icons in the System tray settings. You can clearly see which of them are Oxygen or Breeze style.
Can reproduce the issue with Breeze Dark plasma style and Oxygen icons. Color scheme doesn't seem to make a difference. The Oxygen icon theme's inheritance path doesn't include Breeze explicitly; it asks to fall back to hicolor. Clearly that's not actually happening and instead the Breeze icon theme is being injected into the fallback chain somewhere by KIconLoader. However even if I change the theme to explicitly inherit from Breeze, I can still reproduce the issue.
As far as I can tell Oxygen icons never fall back to Breeze, unless the application uses QIcon::setFallbackThemeName("breeze"). Any breeze icons you see are likely leftover cached icons from before switching themes
When I change Oxygen to inherit Breeze icons are colored as expected
Can confirm, so I guess this is the usual icon cache invalidation issue plus Oxygen not asking to fall back to Breeze.
Created attachment 176799 [details] System tray popup in Plasma 6.2.2+ Situation is much better since upgrading to KDE Neon 6.2 (based on Ubuntu 24.04) and Plasma 6.2.2. Now the only illegible icon is Bluetooth (bluetooth disabled variant). Thank you for the improvement!