Menu.prependSubmenu

void prependSubmenu(string label, gio.menu_model.MenuModel submenu)

Convenience function for prepending a submenu menu item to the start of menu. Combine [gio.menu_item.MenuItem.newSubmenu] and [gio.menu.Menu.insertItem] for a more flexible alternative.

Parameters

`label`	the section label, or null
`submenu`	a #GMenuModel with the items of the submenu