code: @Override
      public void renderHead(final Component _component,
                             final IHeaderResponse _response)
      {
          super.renderHead(_component, _response);
          _response.render(RequireHeaderItem.forClasses(DojoClasses.DnDSource, DojoClasses.parser));
  
  
          if (this.type == DnDBehavior.BehaviorType.SOURCE) {
              final StringBuilder js = new StringBuilder()
                  .append("var nSrc = new dojo.dnd.Source(dom.byId('").append(_component.getMarkupId(true)).append("'),")
                  .append("{ accept: ['" + this.dndType + "']});")
                  .append(" aspect.after(nSrc,\"onDrop\", function(){\n")
                  .append(this.appendJavaScript)
                  .append("\n});");
              _response.render(OnDojoReadyHeaderItem.forScript(DojoWrapper.require(js, DojoClasses.aspect,
                              DojoClasses.dom, DojoClasses.DnDSource)));
          }
      }
docs: Add the javascriupt to the head of the webpage.
  
  @see org.efaps.ui.wicket.behaviors.dojo.AbstractDojoBehavior#renderHead(
  org.apache.wicket.markup.html.IHeaderResponse)
  
  @param _component component the header will be rendered for
  @param _response rseponse