code: public Packer setFillY(final boolean how) {
          if (how == true) {
              gc.fill = GridBagConstraints.VERTICAL;
              gc.weighty = 1;
          } else {
              gc.weighty = 0;
              gc.fill = 0;
          }
          setConstraints(comp, gc);
          return this;
      }
docs: Add fill=VERITCAL to the constraints for the current component if how ==
  true 1 it if false.