title: How to adjust panel width based on another component in wicket
body: <p>I'm developing a wicket application and want to create a panel which need adjust the width based on another element. </p>
  
  <p>The markup looks like: </p>
  
  <pre><code>&lt;div wicket:id="lazyPanel" style="float: left;"&gt;&lt;/div&gt;
  &lt;div wicket:id="widthSpan" style="float: right; width: 30%;"&gt;&lt;/div&gt;
  </code></pre>
  
  <p>and the related java code is:</p>
  
  <pre><code>final WebMarkupContainer widthSpan = new WebMarkupContainer("widthSpan");
  add(widthSpan);
  add(new AjaxLazyLoadPanel("lazyPanel") {
       public Component getLazyLoadComponent(String markupId) {
            // calculate the width based on widthSpan
            int width = 1000 - widthOf(sidebar);
            return new MyPanel(markupId, width);
       }
  });
  </code></pre>
  
  <p>I know I can use some javascript to get the width of sidebar, but how can I send it back to wicket?</p>