public void add_mnemonic_label (Widget label)
Adds a widget to the list of mnemonic labels for this widget.
(See list_mnemonic_labels). Note the list of mnemonic labels for the widget is cleared when the widget is destroyed, so the caller must make sure to update its internal state at this point as well, by using a connection to the destroy signal or a weak notifier.
a Widget that acts as a mnemonic label for this