Occurs when setting up the application.
The CustomizeLanguagesList event's data class is DevExpress.ExpressApp.CustomizeLanguagesListEventArgs.
When localizing your application, you should list all the languages supported by your application in the configuration file (see Localize Standard XAF Modules and DevExpress Controls Used in an Application). If you need to customize this list while starting the application, subscribe to the CustomizeLanguagesList event. Get the list of the languages specified in the application's configuration file using the event handler's CustomizeLanguagesListEventArgs.Languages parameter.
In the Windows Forms solution template, the WinApplication class' descendant handles this event, to add the language of the current UI culture.