Mac OS X Popup & Hierarchical Menu Patch

[Steven Tamm <steventamm@mac.com>]

I just checked a change in that changes the way menus work on the 
carbon port of OSX.

There's an outstanding support request #101602 to fix the "broken" 
popup menus on Mac OS X (Carbon).  The current release does not have 
hierarchical menus in the popups; instead modeling them using an 
"indentation scheme".  There were a lot of off by one errors, and I 
couldn't figure out a good way to fix it because the menu item counting 
scheme would be radically different if the popup menu has a 
hierarchical menu or not.  I decided to fix it by creating real 
hierarchical menus; this also extends to the main menu bar.  This 
should standardize the behavior of menu items to those of the other 
window systems, and it seems to work.  I would invite other people to 
check the code and test it out.

Thanks,
-Steven