Switch back to GTK2 for now
Switch back to GTK2 for now

Fixes #238

Ref https://github.com/mono/xwt/issues/591

illblew/TrueCraft,SirCmpwn/TrueCraft,illblew/TrueCraft,flibitijibibo/TrueCraft,illblew/TrueCraft,flibitijibibo/TrueCraft,SirCmpwn/TrueCraft,SirCmpwn/TrueCraft,flibitijibibo/TrueCraft