weird constraints on sketcher

[dominictarr]

first I gotta say, I love the 2d sketcher! it's very intuitive!

I was able to find some weird behaviors though, making arcs, joining them with tangential lines (making the shape of a door on my boat) then moving things around, sometimes the circles go inside out...

I can think of ways to solve the problem but not with the currently available constraints.
such a constraint that the center point always be between two bounding lines.