I would agree with Steve that if you grant a user permission to a range of departments, you want them to see all the departments including the details. It would be consistent with the behavior of ranges throughout the Financial Reporter and like Steve said, makes managing access to numerous departments much easier.
As for your comments:
Perhaps the correct method of changing the program so it works the way you and your client would prefer, would be to automatically enable all the individual departments when a department range, wildcard or list is chosen. The next question would be, if you deselect an individual department, does the program need to scan all the ranges and disable all the ranges that include the department to be hidden?
I agree with the first sentence, but I'm not so sure the answer to your second sentence/question is "yes". Because as you pointed out, the ability to see a summarized total without details of certain departments might be desirable.
I think Lyndon and Ken would be good people to ping on this question. I think they both use FX with departmental restrictions and I venture to say this could have a big impact on their clients one way or another. Although, the needs in First Nations tend to focus on individual programs so perhaps the range issue would not be such a concern.