Comment 14 for bug 480220

Just realised one thing, it seems like those modes that has the + sign in xrandrs list (848x480 being the mode choosen by default) has the flickering problems, those other seems stable.

$ DISPLAY=":0" xrandr
Screen 0: minimum 320 x 200, current 1024 x 768, maximum 4096 x 4096
VGA1 disconnected (normal left inverted right x axis y axis)
DVI1 disconnected (normal left inverted right x axis y axis)
TV1 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   848x480 25.0 +
   640x480 25.0 +
   1024x768 25.0*
   800x600 25.0
   480i/60 30.0
   480p/60 60.0
   720p/60 60.0
   1080i/60 30.0
   1080p/60 60.0