The DevExpress ASP.NET Round Panel (ASPxRoundPanel) is able to load panel content on demand via callbacks.
The LoadContentViaCallback property specifies the manner in which content is loaded within its container. If the property is set to true, collapsed panel content is loaded during expansion (the panel is initially loaded without content); Otherwise, the content is displayed during initial load. As you might expect, by using delayed loading, you can improve the response time of your web page when displaying large amounts of information within the Round Panel.
The round panel’s content can be updated on demand programmatically by using the client-side PerformCallback method.
Note that in this example, callback processing is delayed for two seconds in order to demonstrate the capabilities of the DevExpress Loading Panel.