title: Block ui when Loading Page
body: <p>i want to block my ui until values in my drop down not loaded
  my js file code is as follows </p>
  
  <pre><code>$(document).ready(function() {
      // Load All Toll Plazas
      FillInCascadeDropdown({ userType: -1 }, "#ddlTollPlazas", "/Home/GetTollPlazas/" + -1);
  }
  
  function FillInCascadeDropdown(map, dropdown, action) {
      $(dropdown).empty();
      $.blockUI({ message: '&lt;img src="/Content/images/ajax-loader.gif"/&gt;' });
      $.post(action, map, function(data) {
          $.each(data, function() {
              $(dropdown).append("&lt;option value=" + this.Value + "&gt;" + this.Text + "&lt;/option&gt;");
          });
      }, "json");
      $.unblockUI();
  }
  </code></pre>
  
  <p>above code not working on page load.</p>