John-

Cool info. Thanks. I may be posting questions about something similar to you in a few months. ;-)

Check out the ON SHUTDOWN command. This sets what gets executed when your app is closed using the window close button.

Cleaning up at the end of an application depends on the application, of course. But, in your case, just for example, it might mean deleting any temporary tables or indices that got created during the app's execution. It might mean saving any user-specific settings (like Window position, or where they last selected an import file, say) before the app closes.