Opens a submenu of the popover. The name
must be one of the names given to the submenus
of popover with submenu, or
"main" to switch back to the main menu.
gtk.ModelButton will open submenus automatically
when the menu-name property is set,
so this function is only needed when you are using
other kinds of widgets to initiate menu changes.
Opens a submenu of the popover. The name must be one of the names given to the submenus of popover with submenu, or "main" to switch back to the main menu.
gtk.ModelButton will open submenus automatically when the menu-name property is set, so this function is only needed when you are using other kinds of widgets to initiate menu changes.