When you move or rotate an object, check out the distance and angle controls near the bottom of the screen:



These display the distance and angle of the current point from the base point.

You can also enter values there, so if you want to constrain the next point to be 4 units away from the previous one, click down there and enter 4, and you will activate the constraint. (you can also most of the type just type in "4"). Similarly if you want to control the angle for one pick, click in the angle box and enter a value and it will lock to those angles for that pick.

Is that the type of thing that you were looking for?

- Michael