Tested more and I found a way to reproduce it. I'm using Clementine and when I drag some songs from the list, then the launcher unhides and doesn't hide until logout. So far I couldn't find another application that triggers the same issue, even if it seems, that when dragging stuff around, the unhide behaviour is rather heretic . But this is another story which needs more testing and probably another bug report.
Tested more and I found a way to reproduce it. I'm using Clementine and when I drag some songs from the list, then the launcher unhides and doesn't hide until logout. So far I couldn't find another application that triggers the same issue, even if it seems, that when dragging stuff around, the unhide behaviour is rather heretic . But this is another story which needs more testing and probably another bug report.