Hi,
I downloaded the mdim.lsp file but I can't make it work.When you pick on the polyline, an option for editing a polyline will just pop out. I tried it on both model space and paper space but just the same. I'm using Autocad 2007 and I don't know if it has an effect on that. As I see on your attached drawing it's a powerfull tool with regards to my line of work because it reduces my time putting dimensions on all the rebar outlines that I'm making of. I hope you still find time to go through this file.Thanks you.
i'll try take a look at it later today... try making a new an open pline with minimum of 3 segments first, then run mdim on that pline. let me know whats the result.