TreeDiagram.onPropertyChanged Method
        
 Called when a property is changed on the adapter.
 This will not be called during a bulk change, as those properties are set via direct sets to avoid
 this event firing.
 
         
        Parameters
        
            - propertyName
            
 
            - 
                
Type: String
The name of the property that is changing. 
            - oldValue
            
 
            - 
                
Type: Object
The old value of the property. 
            - newValue
            
 
            - 
                
Type: Object
The new value of the property.