title: Datagrid: Post String value into the Cell of a DateTime column
body: <p>I don't know if this is even possible, but I have a large datagrid in my WinForms C# app and I want the user to be able to select any cell and mark it as 'Not Applicable' or some other such note (String).  This is fine when the column contains Strings already, but I can't find away to post a String note into a cell which is in a Column designated for Dates.  Short of converting the whole column of dates into string values, does anyone know of a way to achieve this kind of effect?</p>