ui-component/mouse — pull request #1 by dominicbarnes (2013-11-18 16:59:50+00:00)
Title: Only allow left-click to initiate drag

It seems reasonable to me that only a left-click should initiate a drag session.

An alternative solution is to allow a user to call "prevent default" on the mousedown event, and have the `mouse` component interpret that as "do not allow dragging". (although, I think only allowing left-clicks is expected behavior for draggables)