Bug 513007

Created attachment 187390 [details]
bt full from gdb, and debugger log from qtcreator

SUMMARY
When Konsole is pumping a lot of text to stdout and is open on different desktop, it crashes on this line in TerminalScrollBar.cpp:
```
display->scroll(0, display->terminalFont()->fontHeight() * (-lines), scrollRect);
```
Show/hide scrollbar in settings makes no effect.

Commenting out this line resolves the issue (but without proper scrolling Konsole becomes unusable)


STEPS TO REPRODUCE
1. start a long output-heavy process in konsole, compilation for example
2. switch to another virtual desktop
3. wait a bit

OBSERVED RESULT
Konsole crashes

EXPECTED RESULT
Konsole keeps working

SOFTWARE/OS VERSIONS
Operating System: openSUSE Tumbleweed 20251204
KDE Plasma Version: 6.5.3
KDE Frameworks Version: 6.20.0
Qt Version: 6.10.1
Kernel Version: 6.18.0-1-default (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 9 5900HX with Radeon Graphics
Memory: 16 GiB of RAM (15.0 GiB usable)
Graphics Processor: AMD Radeon Graphics


ADDITIONAL INFORMATION
Both Konsole from repos (25.08.3), and from master https://github.com/KDE/konsole

Attached debugger log from QtCreator, and backtrace from gdb