Move unnecessary stuff out of update_image():

Situation: On every call it was checked if it's an animation, picture or if this stuff was already checked.
Normally that should be checked just once. If move_index() is used. Only time self.pixbufOriginal gets a completly new file.
So the check if the loaded animation is really an animation or just a static image is moved to move_index().
In update_image() just remains the check for a pixbuf or pixbuf animation as they're differenly set.
No zoom with PixbufAnimation

pygobject doesn't support scaling with a PixbufAnimation. So if checks included to ignore zoom_delta and zoom_to if it's an animation.
0.5.2
Optimize deletion process

Problem: If at /tmp/pim-trash is already a file with that name, the actual file won't be moved to that location, but will be removed from self.paths + error message.

Easiest solution: Check if the filename at /tmp/pim-trash/ exists and add a random number to that file, then move the new file to trash.
Pro:
 * Just a few lines
Con:
 * New module to import
 * Still possible name collision if random generates the same number again (Chance 1/10000)

Other solution: Using a for loop to add a number. Check if exists, add 1 and check for that filename. If it still exists iterate again, until file can be moved, then continue.