code: private void buildGui() {
  		initWidget(UI_BINDER.createAndBindUi(this));
  		zoomInElement.getElement().setInnerText("+");
  		zoomOutElement.getElement().setInnerText("-");
  		getElement().getStyle().setPosition(Position.ABSOLUTE);
  		getElement().getStyle().setTop(5, Unit.PX);
  		getElement().getStyle().setLeft(5, Unit.PX);
  
  		if (Dom.isTouchSupported()) {
  			initializeForTouchDevice();
  		} else {
  			initializeForDesktop();
  		}
  	}
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