Vaadin portlets, just as all Vaadin applications, use a widget set to render the user interface in the browser and to handle the Ajax communication with the server-side application. While regular Vaadin applications use a widget set for each application, in portals the widget set is shared by all Vaadin portlets running in the portal. Liferay actually comes preinstalled with a precompiled version of the default portal widget set. However, many add-on components come with their own widget set, which needs to be compiled into the portal widget set. The Vaadin Control Panel for Liferay automates this compilation. You can also use it to just install a new version of the Vaadin library.

Open the Vaadin section in the Liferay Control Panel. The initial state with is illustrated in Figure 13.5, “Initial State of Vaadin Control Panel for Liferay”.