Border floating connections

[Wynand Winterbach <wynand dip sun ac za>]

I started using DIA for graph theory related figures, and it's helped a lot.

However, there is one feature that I've always longed for. I'll explain as
follows: 

the edges that are drawn should preferably be connected to the center of a
vertex, and this is easily achieved by defining a custom shape; however, this
only works for when the lines don't have arrow tips on them, so of course what
does happen when we do have arrows, is a situation as follows (where the O's
represent vertices, and there is a line from left to right)...

      \
O------0
      /

instead of

     \
O----->0
     /

The solution is that either:

a) the edges still get connected to the center of the vertex, but a line
must be coded which "knows" where the object that it is pointing to has
its border, so that it can correctly draw the arrow tip.

b) the whole border of a vertex should be able to serve as a connection
point - this would mean that the exact point of connection would move
smoothly along the border as the other side of the line gets moved.

Is there any way to implement this currently? If so, I'd like to give it
a bash.

--Wynand Winterbach