Is there a way to get a perfectly perpendicular and horizontal line?

[prettyhaus]

I'm trying to figure out how to draw perfectly perpendicular and horizontal lines... I know how to make a straight line but even though it looks right, when I finish the drawing I see that its actually off by a degree or so and for perspective, I'd rather have it exact.

[hypotaxis]

On the mac you hold down the Shift and the Command key and draw the line. It will move in 45 degree jumps. I suppose the Windows equivalent will be to hold down the Shift and the Control key. Experiment a little

Brett

[prettyhaus]

Thank you!