Bad VLC window redraw with HiDPI screen: black lines

I have the following problem with VLC 3.0.0 (RC) on HiDPI screens. This problem can also be reproduced on non-HiDPI screens by using QT_SCALE_FACTOR=2 (whose goal is to regard the screen as HiDPI and apply the scale factor).

When I move a window over a VLC window (such as its main window with the Playlist View or the Help window), either from right to left or from bottom to top (but not in the other direction), I get black lines (vertical in the former case, horizontal in the latter case):

from my Debian bug report: Debian Bug#884953.

Note: My window manager is fvwm.

I could reproduce this bug on machines with:

  • NVIDIA Corporation GK208GLM [Quadro K610M] (rev a1)
  • NVIDIA Corporation GF119 [NVS 315] (rev a1)

I have a third machine where I do not use nvidia-driver, on which I could not reproduce the bug.
nvidia-bug-report.log.gz (70.7 KB)