Bit shifting

I always forget that shifting positive integers and negative integers always rounds down (not towards zero), such that 126705>>3 = 15838, but -126705>>3 = -15839, which, of course can be subtle but disastrous for things like, oh, I don't know, rasterization fill conventions. Its supposed to be "live and learn", but it seems like "live, rinse, and repeat"... fixed precision computer math requires surprisingly high attention and focus...

... sigh...

But even that aside, as someone recently pointed out to me, preserving symmetry and sub-pixel accuracy is still an unsolved problem (font hinting could be considered a special case of this domain). I think its not a rasterization problem, but a geometry problem - context matters.