Comment 11 for bug 416294

thanks for your explanations !
It's more tricky than I thought ^_^

So if I understood correctly, using RGBA visuals for video widgets make them fail, so the solution would be to allow to create specifically RGB widgets, which is not possible at the moment because Qt decides by itself if the visual will be RGB or RGBA.
It would explain why Mplayer and Totem works correctly with Cairo-Dock, and also all Qt applications which don't use video like Kate or Konsole, but not VLC or Smplayer.
but then each application should use this new function (or add this new parameter when creating their widget), so we have to report the bug on every Qt applications which use video.

Do your patch (putenv( "XLIB_SKIP_ARGB_VISUALS=1" );) have the same effect as asking Qt to use an RGB visual for the widget ? Would it be applicable for all the impacted applications ?