Created attachment 126065 [details]
Intel Modesetting driver

SUMMARY

Resizing animation of a browser's window is horrible, the window shakes like a jelly and in not a nice way. The biggest issue is however the WHITE GAP BETWEEN TITLEBAR AND THE REST OF THE WINDOW that shows up when we resize down when using Intel Modesetting driver that adds to the jumpy effect.


STEPS TO REPRODUCE
1. Use Intel Modesetting Xorg session and then try the same under Nvidia.
2. Open any browser and set to your favorite search engine (it works everywhere but to keep it comparable, let's stick to search engines).
3. Grab the left or right bottom corner, and resize the window making rotating moves.

OBSERVED RESULT

The content's of the window is shaking and animation is not smooth. It may be the browser's issue. However, with Intel Modesetting driver, we can see at moments a white gap between titlebar and the rest of the window that closes quickly, adding to the jumping effect. Most probably this is the effect that we need to debug and fix. That issue with white gap is not present on Nvidia but resizing animation on a browser is ugly anyway.

EXPECTED RESULT

No white gape and resize effect should look smoother.

I can't be sure but I never noticed it before Plasma 5.18, so I don't know the bug was there before, but it somehow popped up after installing the update so it's possible something got worse.


SOFTWARE/OS VERSIONS
Operating System: Manjaro Linux 
KDE Plasma Version: 5.18.0
KDE Frameworks Version: 5.67.0
Qt Version: 5.14.1
Kernel Version: 5.5.4-1-MANJARO
OS Type: 64-bit
Processors: 8 × Intel® Core™ i7-6700HQ CPU @ 2.60GHz
Memory: 7,6 GiB

ADDITIONAL INFORMATION

I specifically disabled wobbly windows effect to show that this doesn't influence the bug.

I'm posting two videos showing this problem. One with Intel Modesetting, the other one with Nvidia. Excuse me that the vids are short, I had to keep them short to get small size needed for bugzilla.