The add-on provides a component extension which will highlight the extended component in the browser with an eye-catching label containing the fully qualified class name of the extended component or a user-defined text. By that, you can see which part of your UI is implemented by which Java class directly in the browser. The extension is only active when the Vaadin application is run in debug mode. In production mode, the add-on will have no effect. The file download contains all JavaDocs and documentation.