How do you set line length?
 

I finally figured out how to show line length by searching the forum <%length%>. I am drawing a pair of brackets with holes a specific spacing apart. Easy enough in Visio, a real challenge in Omnigraffle. In Visio I can set a specific line length, and drag the center of a circle directly on the end of the line. In Omnigraffle I can't seem to set the length of a line, or drag a circle center onto the end of a line. This also makes it difficult to set measurement lines.

How do you set line length?

If you use Command-R to show rulers, there are some text fields above the top ruler that allow you to type in precise measurements. You can turn on Smart Alignment Guides under Arrange->Guides.