[WillAdams]

I think you win the internet today --- I missed that discussion:

https://news.ycombinator.com/item?id=44118159

(this discussion seems to have aged out https://news.ycombinator.com/item?id=44040642 )

and it's almost exactly what I want (just needs to be a stand-alone desktop app, and have tools for arc and Bézier curve (so that a user could extend arc into a circle, and I assume line into a rectangle) --- if it added Flash-like deforming line-drawing (see Wick Editor for an implementation) that would be icing on the cake.

Thanks!