Hello Herb,
I agree with Steve. The backspace and F5 behavior is completely associated
with client-side webbrowser. HTML page or ASP.NET web page's content or
httpheader has no option to control this behavior. Also, as far as I knew,
browser seems hasn't such key mapping and they're fixed and associated with
certain toolbar button or menu.
Sincerely,
Steven Cheng
Microsoft MSDN Online Support Lead
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