I agree with IDMWALAYDWIA, being a long-time Corel user (yeah, I know...) they have a very efficient way of changing the zero ref of the guides to any place on your drawing, just go to the left top of the guides and drag this corner to where you like, e.g. let it snap to the left top of the rectangle you are drawing and use this to exactly draw the size you had in mind. I want to get rid of Corel completely, but I hesitate. Because I do quite a few technical documentation stuff this would help alot.
I may have missed something similar is possible in Designer but did not find it.
Reg's
Jacques