Required library edition:

The event occurs when opening initiated, but not started yet. (in case of dyn. loading - before xml loading)

This event passes the following parameters:

• id - id of the node that will be opened/closed;
• state - current open state of tree item; -1 means that the item is closed, 1 - item is opened.

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

This event returns: true - confirms opening/closing; false - denies opening/closing.