code: private Rectangle getVDropLineRect(JTable.DropLocation loc) {
          if (!loc.isInsertColumn()) {
              return null;
          }
  
          boolean   ltr  = table.getComponentOrientation().isLeftToRight();
          int       col  = loc.getColumn();
          Rectangle rect = table.getCellRect(loc.getRow(), col, true);
  
          if (col >= table.getColumnCount()) {
              col--;
              rect = table.getCellRect(loc.getRow(), col, true);
              if (ltr) {
                  rect.x = rect.x + rect.width;
              }
          } else if (!ltr) {
              rect.x = rect.x + rect.width;
          }
  
          if (rect.x == 0) {
              rect.x = -1;
          } else {
              rect.x -= 2;
          }
  
          rect.width = 3;
  
          return rect;
      }
docs: Get the vertical drop line rectangle.
  
  @param  loc the drop location.
  
  @return the rectangle.