vb.net - how to automatically close javascript prompt boxes

How would I go about having my application a开发者_如何学Cutomatically close an onbeforeunload prompt box that warns you before leaving the page?

Example: http://sharecash.org/download.php?file=234324234324324324 (try leaving or closing the page)

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I wrote a (freeware) program to handle this sort of thing, its called A Form Filler ( www.aformfiller.com ) - basically all you do is watch for the form to appear and when it appears send the keys strokes.

In this case send a L and an Enter.