For 0.3.0

  - XfmpcGoodies (display artwork, ...), a plugin interface

Unpredictable future

  - Replace the separator between Interface and ExtendedInterface against a
    thin button that is used to show/hide ExtendedInterface
  - Replace the progress bar against something fun, a somewhat better slider
  - Reorder a song in the playlist (with DnD)
  - Editable shortcuts (accelerator maps from file)
  - Document the code (with gtk-doc syntax)

