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