Added some animations for when the pie menus initially appear.
Just for the sake of testing, the top-level (main menubar) menu
opens with the "expand" animation, which gradually expands the
menu options outwards from the central apple disc:
Any submenus of the main menu open with the "sweep" animation,
gradually revealing the menu options sweeping clockwise from
the start of the topmost slice:
Here's a <a href="http://mattgemmell.com/images/pie/pie_menu_animations.mov">Quicktime movie of both animations</a>
(.mov, about 630k; <a href="http://www.apple.com/quicktime/download/">get Quicktime here</a> if you're not on a Mac).