The ASPxPopupControl has the capability to load the content of popup windows on demand. Several content loading modes are available from the following settings of the LoadContentViaCallback property.
- None - The content is always (initially) rendered inside popup windows (the default behavior).
- OnPageLoad - The loading of popup window content starts immediately after the entire page has loaded.
- OnFirstShow - The loading of popup window content starts when a popup window is invoked for the first time.
Using a postponed load of popup window content, you can enhance the response time of your web page on its initial load. You can also update the content of popup windows programmatically, on demand.
Note that in this example, we intentionally pause callback processing on the server side for a second, in order to make the 'Loading Panel' visible during this time.