 - Implement a fallback properties-dialog, for when thunar is not available
   (it happens, bug #4054)

 - Implement file-monitoring, to track an opened file even when it moves
   across the filesystem. The thunar-properties dialog allows renaming
   of the files, using that dialog makes ristretto lose track of an
   opened file at runtime.

 - Try the possibilities of replacing the thumbnail-bar with an iconview
   widget.

 - Write documentation

 - Refactor main-window code, it is a mess.

 - ... whatever pops up on http://bugs.xfce.org/
