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ASPxPopupControl.LoadContentViaCallback Property

Gets or sets a value specifying the content loading mode for the ASPxPopupControl.

Namespace: DevExpress.Web

Assembly: DevExpress.Web.v22.2.dll

NuGet Package: DevExpress.Web


public LoadContentViaCallback LoadContentViaCallback { get; set; }

Property Value

Type Default Description
LoadContentViaCallback None

One of the LoadContentViaCallback enumeration values.

Available values:

Name Description

Specifies that the content is always (initially) rendered inside popup windows.


Specifies that loading of popup window contents starts when a popup window is invoked for the first time.


Specifies that loading of the popup window contents starts immediately after the entire page has been loaded.


Use the LoadContentViaCallback property to control when a popup window’s content should be loaded - always, on page load, or when the window is first shown.

Using the postponed load of popup window contents (by setting the LoadContentViaCallback property to LoadContentViaCallback.OnPageLoad or LoadContentViaCallback.OnFirstShow), you can enhance the response time of your web page on its initial load.

Note that you can also update the content of popup windows programmatically, on demand (by using the client ASPxClientPopupControlBase.PerformCallback method).

On-demand window loading is realized by sending a callback to the server for the popup window’s content. During callback, a specific loading panel can be displayed within the window.


The LoadContentViaCallback property does not influence the ASPxPopupControl loading content process if the content is specified via the ASPxPopupControlBase.ContentUrl or PopupWindow.ContentUrl property.


The ASPxPopupControl does not have the built-in capability to resize nested controls when it is resizing. This example illustrates how to automatically resize controls places inside the popup.

To accomplish this task, execute the following steps:

  1. Set the ScrollBars property to Auto. This option allows the popup control to evaluate the content width and height.

  2. Handle the AfterResizing event. In the event handler, call the AdjustControl method for a desired control to force it to reevaluate its size.

  3. Place the control into the <div style="height: 100%; width: 100%; overflow: hidden"> element. This element is necessary to overcome scrollbars that can be shown when ScrollBars="Auto" is set.

View Example: How to resize ASPxSplitter placed inside ASPxPopupControl when resizing ASPxPopupControl

function OnClick(s, e) {
function OnAfterResizing() {
<dx:ASPxPopupControl ID="ASPxPopupControl1" runat="server" Height="500px" Width="500px"
    ScrollBars="Auto" AllowResize="true" LoadContentViaCallback="OnFirstShow">
    <ClientSideEvents AfterResizing="OnAfterResizing" />
        <dx:PopupControlContentControl ID="PopupControlContentControl2" runat="server" SupportsDisabledAttribute="True">
            <div style="height: 100%; width: 100%; overflow: hidden">
                <dx:ASPxSplitter ID="ASPxSplitter2" runat="server" Width="100%" Height="100%" ClientInstanceName="splitter">
                                <dx:SplitterContentControl ID="SplitterContentControl3" runat="server" SupportsDisabledAttribute="True" />
                                <dx:SplitterContentControl ID="SplitterContentControl4" runat="server" SupportsDisabledAttribute="True" />
<dx:ASPxButton ID="ASPxButton1" runat="server" AutoPostBack="False" Text="Show PopUp">
    <ClientSideEvents Click="OnClick" />
See Also