Make straight lines?
 

Is there a way to ensure that the lines you make with the Line Tool are straight? When I try to draw a straight horizontal or vertical line with the tool using my track ball, my hand sometimes shakes which throws the line off causing me to have to delete and redraw it. I believe that with Visio you could hold down a key which ensures that the line is drawn straight. It would be nice if OmniGraffle has this feature.

Thanks.

Hold down shift while you're dragging. This will constrain it to horizontal, vertical, or 45 degrees.