Safari and Firefox differ in event handling behavior when placing <div> elements inside <button> elements.
* STEPS TO REPRODUCE
1. Open attached test case and click within the red block.
In Firefox, the button gets the event. In Safari both the div *and* button receive events.
Created attachment 16868 [details]
The comportament of Firefox is similar in Internet Explorer 6, and Opera 9.63 whitch I presume it is correct one.
See also: bug 89041, bug 99712.