This has been troubling me for some time now, and thanks to Justin, it’s finally solved!!!
I won’t poach his code, go take a looke. the jist is that in some cases, DataGrid columns marked as visible=false, will be displayed. I had just such a situation in an app I have to maintain. I was seriously worried I’d have to start it over or leave odd functionality in place, since I’m now in my last week here. Glad I can leave the app better than I found it in this one situation.