I am using the code as below,

        var oldItems1 = eventArgs.getOldSelection();

        var newItems1 = eventArgs.getNewSelection();

        // to unselect All

        if (sender._activeItem.get_value() == 'All' && oldItems1[0] != null && oldItems1[0].get_value() == 'All') {

            for (var i = 1; i < sender.get_items().getLength(); i++) {

                var item = sender.get_items().getItem(i);

                item.unselect();

                item.get_element().childNodes[0].checked = false;               

            }

        }

        // to select All

        else if (sender._activeItem.get_value() == 'All' && newItems1[0] != null && ((oldItems1[0] == null && newItems1[0].get_value() == 'All') || (oldItems1[0].get_value() != 'All' && newItems1[0].get_value() != 'All'))) {

            for (var i = 1; i < sender.get_items().getLength(); i++) {

                var item = sender.get_items().getItem(i);

                item.select();

                item.get_element().childNodes[0].checked = true;

            }

        }

The above code is working fine if i check and uncheck on the 'All' Check box

The problem is not with the code, u can observe i m using the Infragistics functions,

 getOldSelection()

getNewSelection()

to perform my logic. The above two functions are returning null values when user is double clicking on the Check box and so the code fails. But when user check and unchecked the check boxes the above functions are returning the corresponding selections.

Thank You.

kpavan_prokarma.