For the 1st pane on tmux, I had to do this but can open a window. For 2nd and all the rest of panes, I can't open windows. For example:$ echo $DISPLAY localhost:10.0$ meld . &         [1] 466/usr/lib/python2.7/dist-packages/gtk-2.0/gtk/__init__.py:57: GtkWarning: could not open display  warnings.warn(str(e), _gtk.Warning)/usr/bin/meld:155: GtkWarning: IA__gtk_icon_theme_get_for_screen: assertion 'GDK_IS_SCREEN (screen)' failed  gtk.icon_theme_get_default().append_search_path(meld.paths.icon_dir())Traceback (most recent call last):  File /usr/bin/meld, line 155, in <module>    gtk.icon_theme_get_default().append_search_path(meld.paths.icon_dir())AttributeError: 'NoneType' object has no attribute 'append_search_path'What I did but didn't work:$ unset DISPLAY$ meld . &         $ set DISPLAY localhost:0.0$ meld . &         $ xhost +localhost  xhost:  unable to open display localhost:0.0$ xhost +xhost:  unable to open display localhost:0.0$ unset DISPLAY$ export DISPLAY=localhost:0.0$ sudo apt-get install xvfb$ sudo Xvfb :5$ export DISPLAY=:5
After 2nd tmux pane windows can't be opened
ubuntu;tmux