Expected Behavior: You should be unable to click and drag the 2nd Firefox logo.
What Happens: In Firefox 4 Beta and the Firefox Nightly, the mousedown event on the 2nd Firefox logo isn't cancelled, resulting in the image being dragged.
The mousedown event is prevented here using event.preventDefault().
In Firefox 4 Beta or the Minefield nightly,
the mousedown event is NOT prevented with this second element.
In Firefox 3.6, the mousedown event is prevented.