- let the Phonon KCM check whether the hw: ALSA device already does mixing, only if it does not
   prefer the dmix: device

- add Player dbus interface in MediaObject

- add global setting to pause video when it's not visible

- add a way to request a specific version (>=) from the Backend, so that known to be buggy Backends aren't used

- menu support? DVD media and Matroska files can come with a menu/control track.
  Is any special API needed for that or does clicking on the video suffice?

- Video Overlays (OSD) like: show a rectangle as a play symbol, show the position in
  the file as something like [IIIIIIIII------], and so on

- don't crash:
  - when no backend is available
  - when an iface object isn't available

- consider whether to add a signal to notify when the information for
  availableAudioStreams/availableVideoStreams/availableSubtitleStreams
  is available

look at pavucontrol, gsmartmix
