decorated edges

[touikan math mcgill ca]

I am a math student and find myself making a lot of directed labeled
graphs. I currently use xfig but dia seems a bit faster to use. I was
wondering if it were possible to add an option for lines/curves. In
particular, instead of only being able to specify arrowheads at the
endpoints, it would be nice if there were an option that would add an
arrohead in the exact middle of the line/curve pointing in the tangent
direction. Keyboard hotkeys and an "update" command like in xfig would be
nice as well.

Thanks,
Nicholas Touikan