Drag panning is slightly broken in IE

[sderle]

Drag panning doesn't quite work right in IE. When dragging, the map doesn't move at first, and a circle-with-diagonal-line-through icon is shown. After a mouse up, the map pans until the mouse is clicked again.

[crschmidt]

This may be partially resolved by the commit in r206.

[crschmidt]

17:18:13 < bjoern_> dnd with left mouse button seems h0rked 17:18:23 < bjoern_> consider using setCapture for IE

 http://msdn.microsoft.com/workshop/author/dhtml/overview/mousecapture.asp

[sderle]

The problem was that the mousedown event was triggering dragstart in IE, which obfuscated mousemove and mouseup. Fixed by r310, which disables dragstart on every div attached to an Events object.