[macosx] JWindow does ignore setAlwaysOnTop property

http://java.net/jira/browse/MACOSX_PORT-158 submitted 2011/07/13 by Yuri Nesterenko
JWindow setAlwaysOnTop(true) doesn't work. It works though for Window.
See an attached simple example. (You will see by the way that JWindow does ignore background color but it's another bug, and not in macosx-port).