the mirror tool is pretty neat for the little bit that i have tried it so far.

RMS, i know that we talked about "cursor size"staying the same as the "object size"
i was wondering if you could put in an option to make it reverse to the other way for the
"drag and move brushes"(just have it as an option not always) i personally like the cursor to "float in size" depending
on the "zoom" of my object..
reason being i can "zoom out" a whole bunch then my cursor gets really big(bigger than yours allows)
and it makes it easy to get silhouettes shaped quickly.
doing it this way IMHO is faster than trying to change the size of the brush all the time.
keep pluggin away, you're making good progress.

oh and i have seen you point out QT as reasons why you couldn't do certain things..
(someone had a problem with Russian language for example, and then funky tablet issues..)
are you dependent on them?(QT) i mean could you transition to something else?
we could get some anti-aliasing(4x would be fine).