Gtk-CRITICAL and Gdk-CRITICAL assertion 'GTK_IS_WIDGET (widget)' failed
I have not been able to replicate these msgs, but after I had used nautilus to delete some files in the some folders belonging to the root directory, I discovered this trail of Gtk-CRITICAL and Gdk-CRITICAL
msgs in the terminal.
(nautilus:28377): Gtk-CRITICAL **: 12:23:44.534: gtk_widget_get_mapped: assertion 'GTK_IS_WIDGET (widget)' failed
(nautilus:28377): Gdk-CRITICAL **: 12:23:44.534: gdk_window_is_visible: assertion 'GDK_IS_WINDOW (window)' failed
(nautilus:28377): Gdk-CRITICAL **: 12:23:44.534: gdk_window_show_internal: assertion 'GDK_IS_WINDOW (window)' failed
(nautilus:28377): Gtk-CRITICAL **: 12:23:44.534: gtk_widget_set_opacity: assertion 'GTK_IS_WIDGET (widget)' failed
(nautilus:28377): Gtk-CRITICAL **: 12:23:44.534: gtk_widget_queue_draw: assertion 'GTK_IS_WIDGET (widget)' failed
(nautilus:28377): Gtk-CRITICAL **: 12:23:46.537: gtk_widget_get_mapped: assertion 'GTK_IS_WIDGET (widget)' failed
(nautilus:28377): Gdk-CRITICAL **: 12:23:46.537: gdk_window_is_visible: assertion 'GDK_IS_WINDOW (window)' failed
(nautilus:28377): Gtk-CRITICAL **: 12:23:46.537: gtk_widget_set_opacity: assertion 'GTK_IS_WIDGET (widget)' failed
(nautilus:28377): Gtk-CRITICAL **: 12:23:46.537: gtk_widget_queue_draw: assertion 'GTK_IS_WIDGET (widget)' failed