Creates a new GtkToggleButton containing a label.
The label will be created using [ctor@Gtk.Label.new_with_mnemonic], so underscores in @label indicate the mnemonic for the button.
the text of the button, with an underscore in front of the mnemonic character
a new GtkToggleButton
ConstructionException GTK+ fails to create the object.
See Implementation
Creates a new GtkToggleButton containing a label.
The label will be created using [ctor@Gtk.Label.new_with_mnemonic], so underscores in @label indicate the mnemonic for the button.