(iTest:27014): GLib-GObject-WARNING **: invalid (NULL) pointer instance
(iTest:27014): GLib-GObject-CRITICAL **: g_signal_connect_data: assertion `G_TYPE_CHECK_INSTANCE (instance)' failed
(iTest:27014): Gtk-CRITICAL **: gtk_settings_get_for_screen: assertion `GDK_IS_SCREEN (screen)' failed (iTest:27014): Gtk-WARNING **: Screen for GtkWindow not set; you must always set a screen for a GtkWindow before using the window (iTest:27014): Gtk-WARNING **: Screen for GtkWindow not set; you must always set a screen for a GtkWindow before using the window (iTest:27014): Gdk-CRITICAL **: gdk_screen_get_display: assertion `GDK_IS_SCREEN (screen)' failed (iTest:27014): Gdk-CRITICAL **: gdk_display_get_pointer: assertion `GDK_IS_DISPLAY (display)' failed (iTest:27014): Gtk-WARNING **: Screen for GtkWindow not set; you must always set a screen for a GtkWindow before using the window
Add display enviornmental variable by eg: DISPLAY=:0.0 Eg: root@spirent:/home# echo $DISPLAY :0.0 Note: Here my PC environmental variable value is :0.0 . So, I have changed DISPLAY value to :0.0 root@spirent:/home# DISPLAY=:0.0 Now open/restart iTest.