It would be very useful if there was a quick way of creating construction lines, ie. infinite lines defined by some parameters. I found http://www.cad-addict.com/2009/01/autoc ... lines.html that describes a bit how AutoCAD does (or did, in 2009) it.
What I have oftentimes is a segment whose line I have to reference things to, but outside the segment itself (pretty sure I don't have the geometry terms right here, but you get the idea), so - at least to me - the most important thing is to have the ability to quickly draw a construction line "on top of" an existing line (but of course it doesn't hurt to have the other drawing tools and options available .
Thoughts? Votes even?