docs: public void setUrl(String url) {
          this.url = url;
  
          if (child != null) {
              child.destroy();
              child = null;
          }
  
          if (url.startsWith("http") || !url.endsWith(".fsp")) {
              child = new Iframe();
              ((Iframe) child).setSrc(url);
          } else {
              child = new Import();
              ((Import) child).setSrc(url);
          }
  
          fullSize(child);
          root.addChild(child);
      }