Hi Michael ...

I don't actually use AutoCad any longer ... when I have to work with .dwg files I use ProgeCad (much less expensive than AutoCad).

Most of my current 2d work is in MoI and/or Rhino.

It seems to me that MoI 'trim' already works well ... one can break or trim pretty much at will ... but I can see the advantage of eliminating the last selection to simply make a break point in line(s) / curves.

eric