ui/src/main/java/ucar/nc2/ui/grid/VertScaleSlider.java
private void setSelectedIndex( int idx) {
    if (zAxis == null)
      return;
    eventOK = false;
    currentIdx = idx;
    slider.setValue( world2slider(zAxis.getCoordValue(currentIdx)));
    eventOK = true;
  }
private void setSelectedIndex( int idx) {
    if (zAxis == null)
      return;
    eventOK = false;
    currentIdx = idx;
    slider.setValue( world2slider(zAxis.getCoordValue(currentIdx)));
    eventOK = true;
  }
set current value - no event