Many forums do this as standard. Say you have a 500 word forum post composed and as you scroll to publish you accidentally hit a link to a "related post" - you're then taken from the page and your text is lost completely. Other sites would pop up a dialogue with something like "Your changes will not be saved, are you sure you want to leave this page?" to preserve the text. This is a critical fix as I see it and should be fast tracked. This frustration is an easy way to lose users.