Debugging painting

I'm trying to debug the painting of my widgets. On Windows I set variables QT_FLUSH_PAINT=1 or QT_FLUSH_UPDATE=1, and this works.

But on Linux I can't get this to work. Is there a workaround this problem, another approach, or does it simply not work on Linux?

It should work. Maybe your window manager causes it to malfunction?

Okay, I will investigate that further. Thank you