Mine

firefox
Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified


(firefox-bin:5336):Gtk-WARNING **: cannot open display:


--------

mythtv-setup
xprop: unable to open display ':0.0'
usage: xprop [-options ...] [format [dformat]] atom] ...

where options include:
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-
-
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Xlib: connection to ":0.0" refused by server
Xlib: No protocol specified 

This option is not available. Please see --help for all possible uasages.