Pixmap view
- Replace zoom step with zoom factor
- Add a color picker
- Scroll with keyboard

File operations
- Save

File view
- Refresh thumbnails
- Multi selection

Dir view
- Show/Hide hidden dirs
- Bookmarks

Misc
- Allow the user to manually define what file should be considered as an image
- Make use of XML GUI (Should hopefully allow to save the state of toolbar
  icons)
