I have been having issues with nomachine
Xlib: extension "Generic Event Extension" missing on display ":1036.0".
it will crash if not root. While trying to make a key (gui wants to pop up).
update: I found that the issue is more then just an annoyance if you, the user, is logged in to the console locally and then you try to use NX (Nomachine).
The errors do not go away but at least the GUI window knows where to pop up at