Assigns a delegate to the beforeCollapse event.
public void addOnBeforeCollapse( 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 beforeCollapse event to that method in the Properties window. The beforeCollapse event occurs when a tree node is about to be collapsed. If the event handler cancels this event, the node will not be collapsed.
See Also removeOnBeforeCollapse