LayerManager.subscribeLayerHiddenChanged Method
        
 Subscribe a callback as handler to layer hidden changed event.
 
         
        Parameters
        
            - callback
            
 
            - 
                
The event handler.
             
            - unsubscribe
            
 
            - 
                
Type: Boolean
True to unsubscribe, False to subscribe. 
        
        Return Value
        
Type: LayerManager
        
This object.