Pop up to ask user before leaving a page if there are unsaved chnages.

Here is the good article to implement this functionality but i was unable to do this with post back buttons in share point web part, it broke all subsequent post backs on page if user clicks "Stay on page", for Hypelinks it works perfectly. I used javascript confirm for postback buttons.

http://snippets.surfthru.com/post/Check-For-Unsaved-Changes-Before-Leaving-a-Page.aspx