Hi Mike, also here's a demo of orient line to line in action:



It's not magic though, it's just bundling up a move plus a rotation plus a scale in a convenient way.

You can get the same result by doing a Transform > Move to first move that small curve so that it has one endpoint on top of the one of the other curve's endpoint, and then use Transform > Rotate to rotate it around that same point to point it how you need it, and then follow that with a Transform > Scale to resize it as well.

Orient line to line just combines those things together with fewer picks - with 2 lines that you pick it incorporates a move from the start point of the base line to the start point of the target line, then a rotation by the angle between the 2 lines, followed with a scale (which you can disable or switch to stretch or uniform scaling mode) by the difference in length between the 2 lines.

It can be particularly convenient if you want to do the kind of endpoint matching shown in the animation above, or also if you want to drop a bunch of copies of objects where you want to rotate and scale each one a little differently. When you turn on "make copies" you will then be able to spit out a rotated and scaled copy of the object by doing just 2 picks for a new target line for each copy.

- Michael