First step to python3
Crude port to pygobject (still using some deprecated stuff). Remaining issues: Keys and positions named after gtk events are gone; segfault with get_width(); checking mimetypes is time consuming. Rest is working more or less.
Replace keysyms with Gdk.KEY
Key bindings reeanbled after changing to the new name.
Removed explicit setting of the scrolling policy. It was changed from NEVER to AUTOMATIC.
Replaced temporary the Gdk.Screen stuff as the get_height and get_width caused segfaults. Static size entry and removed comments from previously disabled entries.
Follow-up on commit f4f986f
Changed default background from black to white. Maybe temporary until a better solution for pictures with no background set. Transparency set or SVGs.
Replaced the size retrieving calls. Instead of getting the size of screen it gets the default screen size. Not really sure about the difference but it doesn't segfault like the other (experienced with python2 and 3 gobject). And I got the values for my screensize.
Divion with / is since python3 (although for python2.2+ available in __future__) true division. No need to change the type.
Port from pygtk (GTK2) to GObject (GTK3) and python3 done.