Setting default for "Allow connections from lines"
 

If I drag a pdf image into an OmniGraffle figure, the default is to have "Allow connections from lines" be checked. Is there a way to have this not be checked as the default for objects that are dragged into OG as a pdf?

You can't set this specifically for images dragged in, I'm afraid. It appears that images dragged in don't abide by the defaults set for the Shape Tool either, so it looks like this is something that could be done, I'll have to poke the engineers about it.