code: protected void setNewHeight(Event event) {
  
          double newheight = m_oldheight + (event.getClientY() - m_clientY);
          if (m_defaultHeight != -1) {
              if (newheight < m_defaultHeight) {
                  newheight = m_defaultHeight;
              }
          }
          ResizeEvent.fire(this, getOffsetWidth(), (int)newheight);
          getElement().getStyle().setHeight(newheight, Unit.PX);
      }
docs: Executed on mouse move while dragging.<p>
  
  @param event the event