void set_label(string label);

Sets label as the label used for the tool button. The "label" property only has an effect if not overridden by a non-NULL "label_widget" property. If both the "label_widget" and "label" properties are NULL, the label is determined by the "stock_id" property. If the "stock_id" property is also NULL, button will not have a label.

See also: get_label()