Created attachment 179872 [details]
display settings

SUMMARY
When I arrange my monitors with one ultrawide (3840x1600) on top and two smaller ones (1920x1080 + 1920x1080) below, using Spectacle in rectangular selection mode causes the selection rectangle to start on one of the bottom screens, even if the cursor is on the top screen.
This issue does not occur when the monitors are placed side by side horizontally.

STEPS TO REPRODUCE

1. Set up your monitors with this layout:
* Top: 3840x1600
* Bottom: 1920x1080 + 1920x1080

2. Open Spectacle.

3. Choose "Rectangular Region" capture mode.

Try to start selecting an area on the top screen.

OBSERVED RESULT
The rectangle begins drawing on one of the bottom screens, regardless of the cursor position on the top screen.

EXPECTED RESULT
The selection rectangle should start exactly where the cursor is, even with vertically stacked monitor layouts.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: openSUSE Tumbleweed 20250328
KDE Plasma Version: 6.3.3
KDE Frameworks Version: 6.12.0
Qt Version: 6.8.2
Kernel Version: 6.13.8-1-default (64-bit)
Graphics Platform: Wayland

ADDITIONAL INFORMATION

Hardware:

CPU: AMD Ryzen 9 9900X (24 threads)

RAM: 60.4 GiB

GPUs: NVIDIA GeForce RTX 3080 
Motherboard: MSI MS-7E16

The issue only happens under Wayland.

>>>>>>> Works correctly when monitors are arranged horizontally.

If you need more information or a video showing the issue, I’d be happy to provide it.