Hello Zorin OS community,
I am facing a persistent and specific issue on my Zorin OS installation and would like to ask for your help in identifying the root cause.
Problem Summary:
A rectangular area in the top-left corner of my screen does not register any mouse clicks. However, this issue is selective:
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Affected Applications: The issue occurs on the desktop (I can't click icons like the Trash can if they are in that corner) and with native system applications (PDF Reader, Settings, Files, etc.), especially when they are in fullscreen and have menu buttons in that specific area.
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The Notable Exception: The problem does not occur when using the Brave browser. Even in fullscreen, I can click on tabs and menus in the top-left corner of Brave without any issue.
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Persistence: The problem is permanent and persists through full system reboots.
Steps I've Already Taken to Troubleshoot:
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I have disabled the "Hot Corner" feature in the Zorin Appearance settings.
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I have rebooted the computer multiple times to ensure it wasn't a temporary glitch.
None of the steps above resolved the issue, which led me to investigate further.
Diagnosis with xwininfo:
To identify what was blocking the clicks, I used the xwininfo utility. After running the command and clicking on the problematic area, I got the following output:
Generated code
xwininfo: Window id: 0x800015 "mutter guard window"
Absolute upper-left X: 0
Absolute upper-left Y: 0
Relative upper-left X: 0
Relative upper-left Y: 0
Width: 1920
Height: 1080
Depth: 0
Visual: 0x3b
Visual Class: TrueColor
Border width: 0
Class: InputOnly
Colormap: 0x0 (not installed)
Bit Gravity State: ForgetGravity
Window Gravity State: NorthWestGravity
Backing Store State: NotUseful
Save Under State: no
Map State: IsViewable
Override Redirect State: yes
Corners: +0+0 -0+0 -0-0 +0-0
-geometry 1920x1080+0+0
My Conclusion So Far:
The xwininfo output clearly identifies a Mutter security window as the element intercepting the clicks. Since the problem persists after reboots, I conclude this is not a crashed process, but rather an application or service that is launching automatically at startup and persistently enabling this "guard window".
My Question for the Community:
My suspicion falls on a startup application (I have already checked the list in "Startup Applications" and haven't found an obvious culprit).
Is there a way, perhaps via the command line or another diagnostic tool, to identify exactly which process or service is spawning this specific "mutter guard window" at boot?
Any help or guidance on how to track down the program causing this behavior would be greatly appreciated.
Thank you.