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Using RadWindow as Controls Container

Since the Telerik® UI for ASP.NET AJAX Q3 2009 release, RadWindow can be used as controls container. This feature is useful for scenarios where you need to have the content in the same page where the RadWindow is declared. When used in this manner, RadWindow acts like a standard container element.

The content of the window is declared in its ContentTemplate tag.

The controls inside can be accessed directly from the page without first going through the ContentContainer of the RadWindow, for example:

<telerik:RadWindow RenderMode="Lightweight" runat="server" id="RadWindow2" VisibleOnPageLoad="true">
        <asp:Label ID="Label1" Text="" runat="server" />
<asp:Button ID="Button2" Text="Set text to the label" OnClick="Button1_Click" runat="server" />
protected void Button1_Click(object sender, EventArgs e)
    Label1.Text = DateTime.Now.ToString();
Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Label1.Text = DateTime.Now.ToString()
End Sub

For more complex scenarios (e.g. accessing user controls and casting them to their type) or to add controls you can use the full hierarchy of the control tree:

<telerik:RadWindow RenderMode="Lightweight" ID="RadWindow1" VisibleOnPageLoad="true" runat="server">
        <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
        <asp:Button ID="Button1" runat="server" Text="Click me" OnClick="Button1_Click" />
protected void Button1_Click(object sender, EventArgs e)
    //Get the TextBox control in RadWindow's Content template
    TextBox mybox = RadWindow1.ContentContainer.FindControl("TextBox1") as TextBox;
    mybox.Text = DateTime.Now.ToString();
    //Add new control to RadWindow's Content template
    RadWindow1.ContentContainer.Controls.Add(new LiteralControl("Dynamic Control"));
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs)
    'Get the TextBox control in RadWindow's Content template
    Dim mybox As TextBox = TryCast(RadWindow1.ContentContainer.FindControl("TextBox1"), TextBox)
    mybox.Text = DateTime.Now.ToString()
    'Add new control to RadWindow's Content template
    RadWindow1.ContentContainer.Controls.Add(New LiteralControl("Dynamic Control"))
End Sub

The RadWindow in this case is only an INaming container and thus using the controls inside via JavaScript requires their correct Client IDs:

<telerik:RadWindow RenderMode="Lightweight" runat="server" id="RadWindow3" VisibleOnPageLoad="true">
        <asp:Label ID="Label2" Text="" runat="server" />
<asp:Button ID="Button3" Text="Set text to the label" OnClientClick="setText(); return false;" runat="server" />
<script type="text/javascript">
    function setText()
        $get("<%=Label2.ClientID %>").innerHTML = "new text";
  • When used as a container the RadWindow is an INamingContainer and behaves like such

  • You can dynamically add controls to the RadWindow from code-behind by adding them to its ContentContainer as shown below: UserListDialog.ContentContainer.Controls.Add(new LiteralControl("Dynamic Control"));

  • To use the RadAjaxManager control in integration with a RadWindow as demonstrated in this demo you should use a separate RadWindow control and not to wrap it in a RadWindowManager. As to using with the standard MS AJAX, it should be used as all other INamingContainers. More information on using AJAX with the ContentTemplate of the RadWindow is available in this help article.

  • When controls with complex server life cycle are placed in the ContentTemplate (e.g., a RadGrid ), such RadWindows should be kept outside of a RadWindowManager. The manager maintains the Windows collection and sometimes needs to Clear() and recreate it, which can cause unexpected behavior with the server logic of the complex controls inside.

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