Created attachment 180670 [details]
a short demonstrative video with vocal narration

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SUMMARY
if you open steam and then focus another window on the desktop using the task manager, hovering your mouse in the top left corner of the new window can sometimes produce steam UI showing up through the window when it should not do this. It does not matter if gpu acceleration is on for the steam client, it persists regardless. I'm using click to focus window behavior but it's agnostic to that. 

STEPS TO REPRODUCE
1. Install and open the steam client. make sure steam is focused. 
2. Open any other application window and focus it using the task manager.
3. Move your mouse around in the top left section of the new window, it will reproduce better if you move the mouse fast. 

OBSERVED RESULT
Steam menu drop downs appear where they should not. 

EXPECTED RESULT
Steam stays idle and the menu drop downs do not activate. 

SOFTWARE/OS VERSIONS
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: openSUSE Tumbleweed 20250420
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.13.0
Qt Version: 6.9.0

ADDITIONAL INFORMATION