private final OperationHandler operationHandler = new AbstractOperationHandler() {
    @Override
    public void handleSet( JsonObject properties ) {
      JsonValue textValue = properties.get( "text" );
      if( textValue != null ) {
    	String oldText = text;  
        text = textValue.asString();
        if(!text.equals(oldText)){
        	Event e = new Event();
			e.type = SWT.Modify;
			e.data = CKEditor.this.text;
			e.widget = CKEditor.this;
			for (Listener l : CKEditor.this.listeners ) {
				l.handleEvent(e);
			}
        }
      }
    }
  };