gtk:popover-menu-bar-add-child (menubar child id)

menubar -- a gtk:popover-menu-bar widget
child -- a gtk:widget object to add
id -- a string with the ID to insert child at

True if the ID was found and the widget added.

Adds a custom widget to a generated menu bar. For this to work, the menu model of the menu bar must have an item with a custom attribute that matches the ID.