Fix about dialog logo leak
Fix configuration options not properly marked as translatable
Fix improper pixbuf lifetime handling

Fixes use of uninitialized value, and use-after-free in fallback code.
Avoid GTK namespace pollution
Speed up some private data access

Avoid all unnecessary uses of G_TYPE_INSTANCE_GET_PRIVATE() as it is a
*lot* slower than direct object->priv access.
Don't leak task title text attributes
Use proper event time when closing a window in response to button click