title: How to determine user has clicked DataGridView but not a Cell
body: <p>I want to prompt the user to enter new elements into a databound collection when they click in the empty area of a <code>DataGridView</code>.  How can I find out if the user has clicked inside of the <code>DataGridView</code> (the grey area by default), but not in a <code>Column</code>/<code>Row</code>/<code>Cell</code>?</p>