Hi, Valeriy, you make a good point. I added more entities so that I wouldn't have to think about Apple's mix of coordinate systems again, or there high-level functions that (to me) were rather weird and counter-intuitive.

So now that the additional work is in place, the complexity (for me) is reduced for day-to-day work. If I add another coordinate system, I just have to name it, figure out where the origin is, and figure out which way the X-axis points.