Created attachment 106393 [details] screenshot My screenshot shows some affected programs handbrake blender opera browser virtualbox clementine player vivaldi browser krita chromium I tested several icon themes. I use Arch, plasma 5.10.3.
KWin uses the window icon as specified by the window. The task manager cares more about applications than the icons and thus tries to prefer the application icon. The difference is expected and wanted by having KWin focus on the window. The main idea is to allow multiple windows to have different icons.
Thank you Martin. As a final user, I don't understand the advantage of this behavior. I think the same program should be represented by the same icon anywhere in the system.
I agree with you Dr Chapatin, but throughout the Linux world there's this weird mania to apply custom icons to programs and override the icons their developers specify. I don't understand it either, but apparently a lot of people like this, despite the visual inconsistencies it causes in cases like this.