code: public Packer pack(final Component cp) {
          if (container != null) {
              container.add(cp);
          }
          comp = cp;
          gc = new GridBagConstraints();
          setConstraints(comp, gc);
          return this;
      }
docs: Establishes a new set of constraints to layout the widget passed. The
  created constraints are applied to the passed Component and if a
  Container is known to this object, the component is added to the known
  container.
  
  @param cp
  The component to layout.