For several hours scratching their heads on the same problem:
http://jsfiddle.net/6kLvLjqr/29/
If drag "sortable 2" "droppable 2", everything works
fine. But if you drag the "sortable 12" to "droppable
2",
using only the scroll wheel mouse
, there are problems. After scrolling you need to move the cursor
outside div.cont and only if the element "droppable 2" will
take "sortable 12".