title: Telerik RadComboBox only opens on the second click
body: <p>I'm new to telerik components, and I have a strange problem.</p>
  
  <p>I'm populating a <code>RadComboBox</code> through JS by calling <code>requestItems</code> based on another combobox selection.</p>
  
  <p>The data populates correctly, but visually only when I click on the combobox a second time does the list appear.</p>
  
  <p>In the source, the data exists, but all the <code>rcbItem</code> have display none , and <code>rcbScroll</code> <code>rcbWidth</code> as a <code>height of 0px</code>. Only on the second click does the list appear.</p>
  
  <p>Here's the JS code:</p>
  
  <pre><code>//global variables for the countries and cities comboboxes
  var ouCombo;
  var dsCombo;
  var searchBox;
  
      function pageLoad() {
          ouCombo = $find("&lt;%= UnitRadComboBox.ClientID %&gt;");
          dsCombo = $find("&lt;%= ServiceRadComboBox.ClientID %&gt;");
          searchBox = $find("&lt;%= SearchRadTextBox.ClientID %&gt;")
      }
  
      function loadDepartments(sender, eventArgs) {
          var item = eventArgs.get_item();
          dsCombo.set_text("A carregar...");
          // if a continent is selected
          if (item.get_index() &gt; 0) {
              // this will fire the ItemsRequested event of the 
              // combobox passing the ID as a parameter 
              dsCombo.requestItems(item.get_value(), false);
          }
          else {
              // the - empty - item was chosen
              dsCombo.set_text(" ");
              dsCombo.clearItems();
          }
      }
  
      function ItemsLoaded(sender, eventArgs) {
          if (sender.get_items().get_count() &gt; 0) {
              // pre-select the first item
              sender.set_text("Escolha uma opçao");
              //sender.get_items().getItem(0).highlight();
              //sender.showDropDown();
              var radInput = $find("&lt;%= SearchRadTextBox.ClientID %&gt;");
              radInput.focus();
          }
      }
  </code></pre>
  
  <p>Here's the markup</p>
  
  <pre><code> &lt;telerik:RadComboBox ID="UnitRadComboBox" runat="server" OnItemsRequested="UnitRadComboBox_ItemsRequested1"
              HighlightTemplatedItems="true" EnableLoadOnDemand="true" OnClientSelectedIndexChanging="loadDepartments"
              OnClientItemsRequested="ItemsLoaded" LoadingMessage="A carregar..." Skin="Default"&gt;
              &lt;CollapseAnimation Type="OutQuint" Duration="200" /&gt;
  &lt;/telerik:RadComboBox&gt;
  
  &lt;telerik:RadComboBox ID="ServiceRadComboBox" runat="server" HighlightTemplatedItems="true"
              EnableLoadOnDemand="true" Filter="StartsWith" OnItemsRequested="ServiceRadComboBox_ItemsRequested"
              OnClientItemsRequested="ItemsLoaded" Width="250px" LoadingMessage="A carregar..."&gt;
              &lt;CollapseAnimation Type="OutQuint" Duration="200" /&gt;
  &lt;/telerik:RadComboBox&gt;
  </code></pre>