Please correct me if I am wrong.
To extend a line, I am supposed to use the "measure tool" to create a construction line and then move that single line to where I want it extended to (the end of the construction line).
If I have a couple dozen or so lines to extend to an irregular form or freehand line, I would have to use the "measure tool" for each one individually. There is no way to tell SU to extend a line or selection of lines only to another entity / line, (the way it works in AutoCad).