Isn't there a problem with using vectors all over the place if no current graphics card accelerates these operations? Wouldn't it make Avalon slightly slower than it could be if it used bitmaps (pre-rendered) only?
As for the compositing (both back windows and top windows), Quartz (or rather the drawing methods an application uses) supports compositing drawing of controls inside a window. It will only redraw the part of the view that is necessary and no other. The older method, QuickDraw, did not support this and an entire, large (usually the entire window) region had to be repainted to get the view hierarchy to redraw correctly.
You say that OS X didn't get vector support until Jaguar (10.2). What vector support is this that it got?
And a person much more intelligent than me tells me that Avalon doesn't support context shearing. Is this correct? The genie effect uses shearing.
It'd be super if OS X supported vector everything but right now vector everything is just too slow to base the entire GUI model off of. No matter the platform.