DashboardCanvasService.subscribeSubcanvasHiddenChanged Method
        
 Set a handler to handle the event when this sub-canvas becomes hidden by the parent canvas.
 
         
        Parameters
        
            - callback
            
 
            - 
                
Type: Function
The event handler. 
            - unsubscribe
            
 
            - 
                
Type: Boolean - May be null
(Optional) True to unsubscribe. 
            - once
            
 
            - 
                
Type: Boolean - May be null
(Optional) True to subscribe handler to only run once.