I don't believe it's possible to do that directly through the webbrowser control itself.

The only way to do that would be to edit the Internet Explorer registry values. I'm not certain where the ones your looking for exactly are, but my best guess would be HKEY_LOCAL_USER\Software\Microsoft\Internet Explorer\Settings (or in a key surrounding \Settings).

The only thing I would suggest is that, if you go this route, you have your app remember the values that were already there and then, upon it's closing, return them. I don't think your end users would be happy with having to reset their MSIE settings everytime they use your app.

Regards,
Evan Sims