How do I reuse a rendered string, i.e. render once and past in multiple locations, e.g. paging nav at top and bottom?

[J.-F. Rompre]

 I am trying to do something that should be easy to do, and may already be
 available from the API (I am still usin 1.3.5).

 How can one duplicate rendered strings?

 In other words, I am trying to render once but copy a number of times for
 better performance - e.g., putting a page navigator both at the top and
 bottom of the list (the bottom is simply a label generated from copying the
 rendered top one) or something more complex such as a calendar.

 I tried using IBehavior.onRendered to copy getResponse.toString() for later
 reuse, but myComponent.renderComponent() throws IllegalStateException: Page
 not found - even though I am adding the component to a panel as instructed
 by Component.renderComponent() - any ideas? My code is below.

 I also thought of overriding one of the rendering methods to write directly
 to the response, but Component.renderXXX() methods are all final - there
 has to be a way to do this simply.

 Any ideas?

 Thanks!
 JF

 The containing panel java (groovy) code - 'ppn' is the component we want to
 render only once
 .....//ProductPanel
 //...
        productsContainer.add( products )
         ProductsPagingNavigator ppn = new ProductsPagingNavigator(
 "productsPagerTop", products)
         ppn.add( new MakeRenderedStringBehavior())

        productsContainer.add(  ppn)
        ppn.renderComponent()       //THOWS 'Page not found..." exc.
                   //save the rendering for reuse
        CharSequence ppnOut = ppn.getRendered()
                  //reuse it here
        productsContainer.add new Label( "productsPagerBottom", ppnOut)
 //....

 //***********************************
 The Behavior code attached to ppn above:
 .....// MakeRenderedStringBehavior
     //...
    public void onRendered(final Component component)
    {
  //....
            //  Copy the rendering if this component can store it..
            CharSequence output = response.toString();
            if ( component instanceof IRenderedString )
                ((IRenderedString )component ).setRendered( output);
            webResponse.write(output);
        }
 //....
 //*************************************
 The containing ProductPanel markup:
 <wicket:panel
 ....
 <div class="Products" wicket:id="products" id=""
    <div wicket:id="productsPagerTop" class="Navigation"</div <!--
 rendered --
    <ul
        <li wicket:id="productsList" id=""
             ...
        </div</li
    </ul
    <div wicket:id="productsPagerBottom" class="Navigation"</div <!--
 pasted in--
 </div
 </wicket:panel