In the old NeXTstep days of pswraps, there was this cool PostScript
operator called "composite" that would blit bits in the current
graphics context. So if you were doing a scrolling chart, you would
just have to composite the 99% of stuff you already had on-screen,
and draw the 1% of new data.
Question 1: Does anybody know of the current Quartz equivalent for
doing this? I image that the NSScrollView/NSClipView combination
knows how to do this, but I have not been able to find the function
to do it.
