As you all know we're having some irritating issues with the contractor-feature.
Giants say it will be solved in a future patch, but in the meantime someone has found a non-permanent solution.
I have tested it, and after editing the farms.xml file I now can not tab into other farms' equipment.
I do guess though that the problem will be back when someone contracts someone again. But anyhow, the problem is temporarily solved
Here is a link to the thread in Giants' supportforum, with the solution at the end of the post.
If you see this Nate? PM me