is_pointer
Description:
Whether the pointer is in the controllers widget itself, as opposed to in a descendent widget.
See also [property@Gtk.DropControllerMotion:contains-pointer].
When handling crossing events, this property is updated before [signal@Gtk.DropControllerMotion:GtkDropControllerMotion:enter],
but after [signal@Gtk.DropControllerMotion:GtkDropControllerMotion:leave] is emitted.