menu_model
Description:
The `GMenuModel` from which the popup will be created.
If the menu model is `NULL`, the dropdown is disabled.
A [class@Gtk.Popover] will be created from the menu model with [ctor@Gtk.PopoverMenu.new_from_model]. Actions will be connected as documented for this function.
If [property@SplitButton:popover] is already set, it will be dissociated from the button, and the property is set to `NULL`.