Easy way to add exit verification dialog to your Vaadin Application
Offers simple one line API to define verification dialog shown to user when user is trying to exit or reload page. Can be used to warn if user has any unsaved changes. When changes are save, you can disable dialog with simple one liner.
Adds client side API for disabling exit verification. Can be eg. used when force reloading page after connection error. https://github.com/alump/BeforeUnload/wiki/How-to-disable-verification-dialog-when-connection-error
FYI, modern browsers do not anymore support custom messages, but dialog itself is still shown, with default confirmation message.