Application BeforeClose Event

For a desktop application, this event occurs when a user attempts to close the main form or quit the application. This provides an opportunity to save state or confirm the action. The event message space supplied as a right argument to the callback function contains:

If no callback is provided, the application is closed.

If a callback function is provided, it must decide whether or not to close the application. Closing the application is done explicitly in the callback using the document Close method.

For a web application, this event occurrs when the connection is lost or closed. There is no way to prevent a web application from closing.