*) Still frames don't update the subpicture overlay
*) timing issues 
   - subtitles display at the wrong time or for too short a moment
*) Aspect ratio stuff 
   - matching Pixel aspect ratio from the mpeg data to the subpicture before
     blending for display
   - output format, widescreen, letterbox, pan&scan etc and selecting the 
     correct subpicture stream based on that
   - Write a spec for this.
*) efficiency
   - Use a more efficient format for blending between dvdsubdec and imagemixer
*) Add filler-handler-before-caps-nego as per alsasink to osssink and friends
*) changing current audio or subpicture track from DVD menu has no effect for playbin.
*) Audio sounds like it is 8-bit to start with, quality is bad until pause/unpause or discont.
*) Use custom seek formats for access to the menu, next/prev chapter/angle etc.
*) Limited duration still frames seem to pause for much longer than they should.
*) Jumping directly into a scene from the menu reports wrong timestamp (only sometimes, possibly)

DONE
*) the bug in dvdsubdec 
   - menu highlights are a palette change, not a crop region
*) still frames hanging still even without gst_element_wait 
   - bug
*) seeking in DVDs is broken