Retrive the text string of widget if it is a GtkLabel, GtkEditable (entry and text widgets) or GtkTextView.
valid widget pointer.
new 0-terminated C string, needs to be released with glib.global.gfree.
Deprecated: This testing infrastructure is phased out in favor of reftests.
Retrive the text string of widget if it is a GtkLabel, GtkEditable (entry and text widgets) or GtkTextView.