I just encountered some weird bugs on an cleanly installed archlinux system.
The desktop panel is set to wrong height sometimes in a random fashion.
See the screenshot here please.

Seems that sizeHint() did not return the correct height.
Help from Александр Соколов is really needed.

Did anyone have the same issue?
I already fixed the razor theme support but the problem remains.

BTW, i just fixed pcmanfm-qt and add proper default config for it.
After installing lxqt-common you should see the razorqt wallpaper by default.