Creates a new #GtkRadioMenuItem containing a label. The label will be created using gtk.label.Label.newWithMnemonic, so underscores in label indicate the mnemonic for the menu item.
group the radio menu item is inside, or null
the text of the button, with an underscore in front of the mnemonic character
a new #GtkRadioMenuItem
Creates a new #GtkRadioMenuItem containing a label. The label will be created using gtk.label.Label.newWithMnemonic, so underscores in label indicate the mnemonic for the menu item.