Created attachment 153814 [details]
It's possible to resize from the side that touches screen edges, moving Kickoff off-center

SUMMARY

Now it's possible to resize Kickoff from the side that touches the screen edges, not matter where the panel is. This effectively moves Kickoff to be off-center until you open it again. Back in 5.26.3 the arrow cursor showed up but it wasn't possible to resize from the side that touched the screen's edge.

STEPS TO REPRODUCE
(Check the attached video)
1. On Git Master or Neon Unstable, open Kickoff
2. Hover the cursor on the side that touches the screen edge
3. Click and drag to resize

OBSERVED RESULT

Kickoff gets resized from the size that touches the screen edge. On 5.26.3 the dragging arrow appears (it shouldn't since you can't resize anyway) but it's not possible to resize Kickoff from screen edges in that version. This also only applies to Kickoff. The calendar (which also touches the screen edge) is not affected.

EXPECTED RESULT

It shouldn't be possible to drag from the sides that touch the screen edge, as that effectively moves Kickoff to a position it shouldn't be at (off-center) until you open it again. It should also not show the resizing cursor from edges that cannot be resized, as it did in 5.26.3.

Operating System: KDE neon Unstable Edition
KDE Plasma Version: 5.26.80
KDE Frameworks Version: 5.100.0
Qt Version: 5.15.7
Kernel Version: 5.15.0-53-generic (64-bit)
Graphics Platform: Wayland
Processors: 6 × Intel® Core™ i5-9400F CPU @ 2.90GHz
Memory: 7,7 GiB of RAM
Graphics Processor: AMD Radeon RX 570 Series

ADDITIONAL INFORMATION

Happens on Wayland and Xorg sessions alike, no matter where the panel is.

In 5.26.3 I tested with a 1366x768 screen at 1x scale.
On Neon Unstable I tested on another PC, with a 1920x1080 screen at 1x scale.