code: @Override
      public void deselectAllOptions() throws WidgetException {
          try {
              org.openqa.selenium.support.ui.Select selectBox = new org.openqa.selenium.support.ui.Select(
                      findElement());
              selectBox.deselectAll();
          } catch (Exception e) {
              throw new WidgetException("Error while deselecting all selected options", getByLocator(),
                      e);
          }
      }
docs: /*
  (non-Javadoc)
  
  @see qc.automation.framework.widget.ISelectList#deselectAllOptions()