That is a fantastic discussion on dragging with Javascript. Really appreciate the information.

I've a quick question. How do you restrict the dragging movement to an axis using the built-in DOM events like dragstart/etc. I had a drag & drop feature implemented using the dragstart/dragenter/dragover/drop/etc events. I couldn't find a quick way to restrict the dragging movement to the x-axis. JQuery's drag and drop API used to support it. I'm trying to use the native DOM events/api only. Any information or pointers are greatly appreciated.