I have this strange problem with nvidia-340 driver (version 340.107-0ubuntu0.18.04.3) in Ubuntu 18.04. When I have playback window open on MythTV’s mythfrontend, and I use accelerated graphics profile (VDPAU or OpenGL), and I put another window on having some area of almost black RGB color (2,2,2), that color will be transparent showing image of the playback window behind (even if there is/are yet another window between them).
It happens mainly with MythTV’s mythfronted in my experience. (MythTV version 29.1 from Mythbuntu PPA) It does not usually happen with Kodi, VLC or mplayer, but once I could make (2,2,2) pixels of MythTV’s mythfrontend transparent when stared playing some video by another player before opening mythfrontend for playback.
I have the same problem with another computer that has the same OS and driver but different NVIDIA graphics hardware. The problem was also present with older version of Ubuntu, nvidia-340 driver and MythTV.
This problem does not happen with nouveau driver.
Older video: https://youtu.be/NhJCgTW1pdY
nvidia-bug-report.log.gz (107 KB)