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Custom loading sign for RadWindow

How to

Use a custom loading sign with RadWindow


There are two common scenarios for customizing the default loading animation which is shown while the RadWindow's content page is being loaded or it is autosized - to change only the loading image or to use your own HTML element.

  1. Change the loading image

    In order to get the desired result you should include the image you want to display in the project and then override the default image set to the RadWindow by using a style, similar to the below one:

    • for RenderMode="Classic"
        background-image: url("ImageUrl") !important;   
    • for RenderMode="Lightweight":
    .rwLoading .rwExternalContent
        background-image: url("ImageUrl") !important;   
  2. Use your own HTML element as a loading sign

    This scenario is a little bit more complex and to implement it you should go through the following steps:

    • declare the element which you want to use as a loading sign and set its display to none e.g as shown below:
    <div id="loading" style="border: solid 1px Red; width: 100px; height: 50px; display: none;
      text-align: center; margin: auto;">
      Custom<br />
    • override the default loading to display blank:
    <style type="text/css">
        background-image: none !important;
    • handle the OnClientShow and OnClientPageLoad events to show and hide your custom loading as shown below:
    <script type="text/javascript">
    var loadingSign = null;
    var contentCell = null;
    function openRadWnd() {
        $find("<%=RadWindow1.ClientID %>").show();
    function OnClientShow(sender, args) {
        loadingSign = $get("loading");
        contentCell = sender._contentCell;
        if (contentCell && loadingSign) {
   = "middle";
   = "";
    function OnClientPageLoad(sender, args) {
        if (contentCell && loadingSign) {
   = "";
   = "none";
    <telerik:RadWindow ID="RadWindow1" runat="server" NavigateUrl="ChildPage.aspx" ShowContentDuringLoad="false"
    OnClientShow="OnClientShow" OnClientPageLoad="OnClientPageLoad">
    <%--Button to show the window--%>
    <input type="button" id="btnOpen" value="Open RadWindow" onclick="openRadWnd(); return false;" />

The provided solution with the custom loading works for the case when the loading should be shown while the content page is loading and thus you should make sure that you have ShowContentDuringLoad="false" for the RadWindow.*

The above code works only if the ReloadOnShow property is not set, as appendChild() removes the original content from the document. If you set this property to true a slight modification is needed that utilizes the cloneNode() method instead so that the sign appears correctly on subsequent displays of the RadWindow. You can find an example in the attached archive.*

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