Bug 463237

SUMMARY
When a window is unresponsive, the frozenapp effect is applied and the title has '(Not Responding)' appended. It takes time to determine that a window is unresponsive when a window is focused. When it is marked unresponsive, when it loses focus, it is marked responsive again, unless it loses focus before the unresponsive state is recognised.

I could not determine why this issue occurs. I am not sure if this is a regression, but I suspect that this is not the intended behaviour. Please move the issue from general if this is not the appropriate component.


STEPS TO REPRODUCE
1. Open kwrite
2. `kill -SIGSTOP $(pidof kwrite)`
3. Focus kwrite, becomes unresponsive
4. Unfocus kwrite, window incorrectly loses unresponsive state
5. Focus again, window is now unresponsive
--
6. When refocusing a window, if the window is unfocused again *before* being recognised as unresponsive, it will be correctly recognised as unresponsive in the background, and if focused and unfocused, loses that state as above.


EXPECTED RESULT
The window should not lose its unresponsive state when it is unresponsive and loses focus.


ADDITIONAL INFORMATION
A window becoming responsive is not an issue, regardless of focus (SIGCONT).

Add qDebug() << "unresponsive state: " << (unresponsive ? "true" : "false"); just beneath https://invent.kde.org/plasma/kwin/-/blob/master/src/window.cpp#L3432 to help identify how the unresponsive state changes. Also/alternatively pay attention to the window title, as this change is immediate whereas the frozenapp effect is animated.

This issue is for Wayland. It likely exists on X11 - I have not tested it.