I'm writing a WPF application using VS 2008 for a client that wants to force the users to scan a barcode for data entry into MOST textboxes. But they want a password protected override button on the form that will allow a person to manually enter the text if, for some reason, the barcode is unreadable or the reader is not working.

Does anybody know of a way to ignore data entry into textboxes using the keyboard, but allow barcode scanned text?