I have a customized combobox that I am using in a XamDataGrid by overriding the CellValuePresenterStyle as described in the thread here:

http://forums.infragistics.com/forums/p/33130/181605.aspx#181605

My combobox creates an adorner when the SelectedValue binding source is a value that is not present in the Items of the combobox.  This all works when not in a XamDataGrid.  The behavior is that the source value is displayed in an adorner so the user can leave the value or select another value from the list.

In a XamDataGrid, it seems that the CellValuePresenter.Value becomes null in this case before my custom logic can be executed in my control.  This breaks the desired behavior because the user can never leave the original value intact.

Is there a way to change the behavior of the CellValuePresenter when the source data is not present in the combobox items?  The value should just be left alone, not set to null.

Is there another property I should be looking at other than CellValuePresenter.Value?

Thanks.