Jquery - Sortable : How to prevent the drag should not goes to below after a desied row.

Jquery - Sortable : How to prevent the drag should not goes to below after a desied row.


 Hi All, I have a query that , I am using jquery sortable

http://jqueryui.com/sortable/#default

Open the above link , My requirement is that if any user drag the item 1 in y direction and when the item 3 goes up the y direction drag should be stopped.

Means dragging element should not drag below the  item-3.

Only possible drop area of item 1 is
between item 2 and item 3
between item3 and item 4

help me to do this.