Bug 506668

Summary: Right half screen content overlapped in Spectacle rectangular region selector after disabling left monitor
Product: [Applications] Spectacle Reporter: Ye Jingchen <ye.jingchen>
Component: GeneralAssignee: Noah Davis <noahadvs>
Status: REPORTED ---    
Severity: normal CC: kde, nate
Priority: NOR Keywords: multiscreen
Version First Reported In: 6.4.2   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: spectacle region preview, captured by obs-studio
Screencast demostrating screen content overlap

Description Ye Jingchen 2025-07-06 11:12:45 UTC
Created attachment 183002 [details]
spectacle region preview, captured by obs-studio

SUMMARY
When connected to two monitors and go from both monitors active to disabling the left one, Spectacle's Rectangle Region selector will display right side screen content overlapped onto center, as shown in the screenshot.

STEPS TO REPRODUCE
1. Have two monitors active
2. Disable the left monitor in System Settings
3. Use Spectacle to take a rectangle region screenshot

OBSERVED RESULT
The right side screen content is overlapped onto the center in Spectacle's region selector.

EXPECTED RESULT
Normal preview without the overlap.

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.4.2
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.1
Kernel Version: 6.15.4-arch2-1 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 PRO 6850HS with Radeon Graphics
Memory: 16 GiB of RAM (14.9 GiB usable)
Graphics Processor: AMD Radeon Graphics

ADDITIONAL INFORMATION
When playing with enable and disable monitor's, I notice the virtual desktop switcher (lower right corner in my screenshot) also display incorrect window position: I have the System Settings maximized, but the virtual desktop switcher only shows it on the right side of the monitor, which looks like the portion overlapped onto the center in Spectacle region selector.

Thus I am not sure if the problem is in Spectacle of in KWin.
Comment 1 Ye Jingchen 2025-07-06 11:19:39 UTC
Created attachment 183003 [details]
Screencast demostrating screen content overlap

This is recorded using OBS Studio. In the begining with two monitors active, rectangle region screenshot works normally. After disabling the left monitor, Spectacle rectangle region shows the overlapped screen content. Also notice that after disabling the left monitor, the virtual desktop switch at the lower right corner shows an incorrect window position, as if the left monitor is still active, and truncated the right portion of all screen content.

The overlap screen content goes away if I change scaling factor or screen resolution and change it back.