The RockMelt purpose is to re-imagine the browser for the way people use the Web today. RockMelt does more than just navigate Web pages. It makes it easy for you to do the things you do every single day on the Web: share and keep up with your friends, stay up-to-date on news and information, and search.

From mouse events: mousedown, mouseup and click, dblclick, mousemove and finally mouseover and mouseout. Like wasn’t enough the bad css support, IE have a strange way to look at an event object what is working just fine on any other browser.