Assigns a delegate to the beforeExpand event.
public void addOnBeforeExpand( TreeViewCancelEventHandler value )
value
The TreeViewCancelEventHandler delegate to be notified when the event occurs.
Passing an event handler as a parameter to this method is equivalent to setting the beforeExpand event to that method in the Properties window. The beforeExpand event occurs when a tree node is about to be expanded. If the event handler cancels this event, the node will not be expanded.
See Also removeOnBeforeExpand