References: bnc#907958
Sanity check for those who forget '-X' on ssh and try to start virt-manager
Index: virt-manager-1.2.1/virt-manager
===================================================================
--- virt-manager-1.2.1.orig/virt-manager
+++ virt-manager-1.2.1/virt-manager
@@ -182,8 +182,11 @@ def main():
         from gi.repository import Gtk
         leftovers = sys.argv[1:]
 
-        # This will error if Gtk wasn't correctly initialized
-        Gtk.Window()
+        if os.environ.has_key('DISPLAY') and os.environ['DISPLAY']:
+            # This will error if Gtk wasn't correctly initialized
+            Gtk.Window()
+        else:
+            raise Exception("Error starting virt-manager: No graphical display found")
 
         globals()["Gtk"] = Gtk
         import virtManager.config