Created attachment 166562 [details]
the line appearing in x11

SUMMARY:
a line about a pixel length appears around the bottom and top of the taskbar, effects vary depending the session used (x11, wayland).


STEPS TO REPRODUCE
(x11)
1. set the taskbar to always stay visible 
2. open a window 
3. maximize it

(wayland)
1. open a window
2. maximize it
3. set taskbar to dodge window
4. hover to the bottom to bring back the taskbar 

OBSERVED RESULT
(x11)
- a pixel length line between the taskbar the window.

(wayland)
- around step 2, a line will appear similar to x11. however, this one is black and can trace mouse movement.
- after step 4, a blue line at the bottom of the screen appears and stays there permanently.
EXPECTED RESULT
(x11)
- the window should have covered all of the screen appropriately

(wayland)
- the blue line described above shouldn't have appeared

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux
KDE Plasma Version: 6.0.1
KDE Frameworks Version: 6.0.0
Qt Version: 6.0.2

ADDITIONAL INFORMATION

- on wayland side, switching desktop (ones on the overview menu) removes the blue line. however, it appears again once hovering to the taskbar.

- also on wayland, opening an app pinned to the taskbar will result to corrupted image appearing around the same position of the blue line

- sometimes when switching desktop (ones on the overview menu) it can result into another line of the same length appearing on the right side of the screen when maximizing a window while the taskbar is set to always visible.