code: public Packer setInsetRight(final int val) {
          Insets i = gc.insets;
          if (i == null) {
              i = new Insets(0, 0, 0, 0);
          }
          gc.insets = new Insets(i.top, i.left, i.bottom, val);
          setConstraints(comp, gc);
          return this;
      }
docs: sets right Insets on the constraints for the current component to the
  value specified.