/**
  * Set the minimium date value for all viewers but the emitting viewer.
  *
  * @param emitting emitting viewer
  * @param minDate value
  */
 private void setMinDate(TimeBarViewerInterface emitting, JaretDate minDate) {
   for (TimeBarViewerInterface viewer : _viewers) {
     if (!emitting.equals(viewer)) { // do not set on the emitting viewer
       viewer.removePropertyChangeListener(this);
       viewer.setMinDate(minDate.copy());
       viewer.addPropertyChangeListener(this);
     }
   }
 }