Fix missing Gdk import
Properties window: Fix GTK3 related issues
Associations: return str in get_mime_type
Bookmarks menu: Fix GTK3 issue
Item list: History list: Fix GTK3 issues
Item list: Fix popup menus
Item list: Fix mouse interaction
Rename extensions: Fix GTK3 issues
Main Window: select clipboard before use. set_with_data issue still there https://bugzilla.gnome.org/show_bug.cgi?id=656312
Emblems: Fix GTK3 issues
Merge pull request #58 from ArseniyK/gtk3

Improvements to GTK3 branch.