When running on macOS 10.12+, there are private notification center
messages we can use to reliably detect when a window is being
dragged by its titlebar. These are less finicky than the current
combination of an undocumented event subtype and a left mouse up.
Signed-off-by: Tim Clem <tclem@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>