Hopefully this clears up the confusion between a) visible as in "all
ancestors are expanded" and b) visible as in "within the part of the
tree that is displayed on the screen".

Also, the claim that firstVisible has visible order 0 was false.
Signed-off-by: Joachim Priesner <joachim.priesner@web.de>
Signed-off-by: Nikolay Sivov<nsivov@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>