I've simply been trying to get Sublime Text 2 running on Ubuntu Server 14.04 LTS on a Virtual Machine but also get the same error trying to run gedit so this leads me to believe it's an environment config issue.
Gtk-WARNING **: cannot open display:
I've installed gksu and tried gksu gedit with the same result.
It's really starting to hurt my head. Any suggestions/help much appreciated?