title: javascript update lost on first async update
body: <p>I have an update panel that has a button with a handler:</p>
  
  <pre><code>protected void btn_Click(object sender, EventArgs e)
  {
      ScriptManager.RegisterStartupScript(Updater, this.GetType(), "Hash Update", "UpdateServerData('" +
              avalue + "');", true);
  }
  </code></pre>
  
  <p>and a javascript function:</p>
  
  <pre><code>function UpdateServerData(val) {
      parent.location.hash = val;
  }
  </code></pre>
  
  <p>The first time I click the button after the page loads, the value is written to the location. hash, but is cleared out.  The next click functions the way it should.  I can't figure it out.  Any help appreciated.</p>