Sets the GMenuModel from which the "popup" property will be
filled in, or NULL to disable the button.
The GtkMenu will be created with gtk_menu_new_from_model(), so actions
will be connected as documented there.
If "popup" is already set, then its content will be lost
and replaced by our newly created GtkMenu.
Sets the GMenuModel from which the "popup" property will be filled in, or NULL to disable the button. The GtkMenu will be created with gtk_menu_new_from_model(), so actions will be connected as documented there. If "popup" is already set, then its content will be lost and replaced by our newly created GtkMenu.