all overlay based vo.
Add support for xover to tdfx_vid. Sometimes the display flash bcs
the x server fuckup the overlay settings :( Not so bad as it only append
when i switch the focused window here.
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@9570 b3059339-0415-0410-9bf9-f77b7e298cf2
albeu