If the device if of type gdk.types.DeviceType.Master, it will return the list of slave devices attached to it, otherwise it will return null
the list of slave devices, or null. The list must be freed with glib.list.List.free, the contents of the list are owned by GTK+ and should not be freed.
If the device if of type gdk.types.DeviceType.Master, it will return the list of slave devices attached to it, otherwise it will return null