This event calls user-defined handlers (if there are any) and passes the following parameters:

• id - id of the node that will be opened;
• state - current open state of the item: 0 - item has no child nodes, -1 - item is closed, 1 - item is opened.

        tree.attachEvent("onOpenStart", function(id,state){});
 

The event returns: true - confirms opening|closing; false - denies opening|closing.