The DropDown widget currently uses a ListModel to manage its list of options, and creates a SingleSelection internally. This already goes a long way to making it easier to integrate than the ComboBox widget, but I believe it could be improved further by adding support for externally created SingleSelection models. This would remove the need to connect signal handlers for selection changes. For example (in Gtkmm) using a DropDown in place of a StackSwitcher would become as simple as “dropdown.set_model(stack.get_pages());”.
I might take a look at creating a PR for this myself, but I typically use Gtkmm, so I’m not very familiar with Gtk’s code base.