Ian et al, I have officially given up on this issue. I'm defeated and I told the customer that it would waste money if I kept researching it.
I could replace the CheckBox column with my own bound column type that draws itself to make some kind of mock CheckBox, but that would take hours of work. I told the customer to tell his staff that the workaround is to press the Enter key on the offending cell on the top row. It's stupid but it's easy and it works. This reminds me of the other intermitted "bug" in grids that I create where pressing the Esc key on validation failed cell value doesn't restore the previous value. I've spent hours of my life over the years trying to track this one down without success. Luckily it happens rarely now, and I detect it early and delete the whole control and make a fresh one and it usually comes good. Go figure! I'll be migrating to WPF grids more in the future, so I'll probably run into a whole new suite of weirdness and roadblocks. If I ever find the answer to this I'll let you know. Greg
