Hello,
recently I discover something what makes work in AutoCAD much more easier.
If I have a Polyline and I want to stretch only one Segment of it,
I hold [Ctrl] and Click with LeftMouseButton on this Segment.
This way I can select chosen Segments, one by one.
But I can't deselect the Segments.
If I need three Segments and select four, I can't deselect
this mistakenly selected Segment. Even while holding [Shift] or [Ctrl]+[Shift].
So when I have the Segment chosen, I type MOVE, Enter, and
that is the way to have great fun about how to easy stretch could be.
It works in my computer, on Autocad 2012.
I told it to one girl who has Autocad 2010, but on her computer it didn't work.
So I think that there should be such command which would allow these people who have versions older than 2012 to use this option.
I think about lisp "Stretch Rectangle if it was a Viewport". I think it would be great and very helpful.
But I don't feel I can write such lisp now.
How to define side of Rectangle with picking two Points,
between which this chosen side lies? Please, help me with good advice.
For some situations at least, you may be able to use the attached OffPoly1.lsp routine with its OP1 command. It doesn't do it Stretch-wise, but rather Offset-wise, but with similar results -- specify an offset distance, select the segment you want moved and tell it in which direction to move it. It Offsets that one segment and adjusts the adjacent ones accordingly. And it works in older versions. Read the comments at the top of the file.
When I read your post I remembered lisp "Offset Polyline Section" by Lee Mac:
http://www.lee-mac.com/offsetpolysection.html
It is good to solve this problem, too.