Mouse wheel handling with Prototype

There is a bug wandering the web. If you google for "prototype mouse wheel", you'll find some snippets of code. They are rather good, except for their age. Those are '06-'07 oldies, and we have '09 around. Since the time that code was written, there has been a release of Firefox 3, in which they fixed one tiny wee peculiarity: the value of event detail property, which holds the "amount" of scroll. Before the new version of FF it was +-3 for single wheel turn, which is reflected in the old code as the division of detail by 3, which gives "normalized" wheel move data. FF3 guys thought it was a shame to have 3 as value of detail property while in fact it represents only one wheel turn. So they adjusted it to be nice +-1. The problem is, old code returns zero now, because 1/3 equals 0. I will post my fix for this solution, although it's easy as heck to port it to other one.

delta = !!event.detail*(event.detail>0? 1 : -1);

Now this behaves good both in FF2 and FF3.