You can't.
In general, neither Java
applets nor JavaScript scripts can twiddle browser settings. This is for the very good reason that there are loads of bad people out there, trying to do all sorts of bad stuff to your browser.
Dealing with the Back button is one of the bigger problems of writing clever Web pages, using things like Applets, AJAX etc. You can write your code in such a way that pressing Back has less bad effects. You can also programmatically add/modify history entries, to change what Back does; I'm no expert on this, having only read about it, not done it, and I suspect how well it works varies between browsers and their configurations. Lastly, you can get your app to pop up a new, undecorated window with no Back button; this suffers from (a) user may disable pop-ups, and (b) user can still go Back using keyboard shortcut.
I suggest Googling for stuff about handling the Back button. Also search JavaRanch forums. When you've read a bit and maybe have further questions, try posting in a more appropriate forum, as this is really not much to do with Java in General. Maybe try the HTML/JavaScript one, the
Servlets one, or the Applets one?
[ August 29, 2007: Message edited by: Peter Chase ]
