Minor Grid Steps = 1
 

I am using OmniGraffle Pro 4.2.1 (v129.15).

As far as I can tell, a "Minor Grid Steps" setting of 1 is not accepted. That is, entering "1" leaves a "1" in the entry field, but the displayed grid remains at its previous setting. I don't see a good reason why this should be so; sometimes I want to set a grid of a specific size and don't need or want minor grid lines. A natural way to set a grid of, say, 11pt would be to enter "11pt" in "Major Grid Spacing" and "1" in "Minor Grid Steps", but this does not seem to work. Can this be made to work, please? Or can someone tell me what I need to do to make this work in OmniGraffle?

Thanks!