I am running Ubuntu 18.04 on a Lenovo Thinkpad (LED screen) and can adjust the screen brightness without any issues. However, when watching videos, e.g. on VLC media player or Totem Movie Player, I encounter following problem:
As soon as the full-screen mode is activated, the screen brightness automatically increases to the maximum. If I leave full-screen mode, the brigthness changes back to the previously selected value.
I am wondering whether there is some way to prevent fullscreen applications from altering the previously adjusted system brightness settings.