@Override
 public void mousePressed(MouseEvent e) {
   if (e.getSource() != table) return;
   int row = table.rowAtPoint(e.getPoint());
   if (row >= 0) { // init drag
     GeoElement geo = ((ConstructionTableData) data).getGeoElement(row);
     dragIndex = geo.getConstructionIndex();
     minIndex = geo.getMinConstructionIndex();
     maxIndex = geo.getMaxConstructionIndex();
   }
 }