Fills overlapping borders
 

[IMG]http://data.tumblr.com/8BxAswM5Xiiz15agKJ7CWmPEo1_500.png[/IMG]

Are borders inside the shape, outside the shape, or in between? Is there any way to make this display consistently?

Did you create the central shape first, and since you have the two outer shapes with a bottom border and a right border for the right hand one, is the central shape actually the size of the whole diagram? Do you need it to be so? Do you want the border right round the whole object or only round the central part?
Are you using OG or OGPro? If the latter, can you produce the three shapes without border independently and then 'union' them and put a border round the resulting shape? I don't know ... I'm just guessing and that's what I'd try.

The way OmniGraffle works is to add the stroke with the outer edge of the internal shape as the [I]centre[/I] of the stroke, not with the edge of the internal shape as the inner - or external - edge of the stroke (you can see this for yourself if you magnify your view of a selected shape's edge and e.g. toggle through various dimensions for the stroke while looking at how it appears at the new sizes).

Alas, a consequence of this is that, if you wish to prevent the edge effect you are seeing when snapping shapes without a stroke to a shape with a stroke, you won't be able to do it very easily.

The solution is to add a stroke to the two outlying shapes in your figure but of the same colour as the fill, and of the same width as the stroke in the shape below.

HTH.

I see. It sounds like basic rounding, i.e. the line ends up on one side 50% of the time (top and left) and on the other side the other 50% of the time (bottom and right). I will try the grouping, or just leave the borders off and add a bordered shape on top with no fill to get the look I want. Thanks for the info!