If the frame’s label widget is a gtk.Label, returns the
text in the label widget. (The frame will have a gtk.Label
for the label widget if a non-NULL argument was passed
to Frame.new.)
the text in the label, or NULL if there
was no label widget or the lable widget was not
a gtk.Label This string is owned by GTK+ and
must not be modified or freed.
If the frame’s label widget is a gtk.Label, returns the text in the label widget. (The frame will have a gtk.Label for the label widget if a non-NULL argument was passed to Frame.new.)