Eureka, I've got it!!
I was trying to "change" a textbox type to a checkbox after the
"AutoGenerate" had created it. Turns out I have to turn off AutoGenerate and
create it as a CheckBox type in the first place. It's drudgery but it works.
> Can anyone show me (sample code???) how to programmatically set a column
> type to "CheckBox" in code (as opposed to the designer)? The datagridview
> isn't bound to a design-time dataset so until it executes there are no
> columns for which I can select a column type.