`GtkBinLayout` is a `GtkLayoutManager` subclass useful for create "bins" of widgets.
`GtkBinLayout` will stack each child of a widget on top of each other, using the [property@Gtk.Widget:hexpand], [
property@Gtk.Widget:vexpand], [property@Gtk.Widget:halign], and [property@Gtk.Widget:valign] properties of each child to determine where
they should be positioned.