Reordering subforms in Firefox

[Mark Dexter]

I have an extension that uses the new subform feature to create a repeatable set of fields. Overall it works pretty well. However, the move (reorder) is a bit wonky in Firefox. When you start to drag, the div being dragged jumps way up above the cursor so when you drop you can't see the div you are dropping. It works if you just focus on the cursor and ignore the position of the div being dragged.

In Chrome it seems to work perfectly.

Has anyone else had experience using drag/drop for reorder with subforms? Any ideas or suggestions how to troubleshoot will be greatly appreciated. Thanks.