sbt> vaadin-generate-widgetset
...
sbt> vaadin-compile-widgetset
...
sbt> jetty-run
set logLevel := sbt.Level.Debug
see notes in SBT vaadin plugin and add the declared widgetset in web.xml
<servlet>
<servlet-name>ScalaadinApplication</servlet-name>
<servlet-class>com.vaadin.terminal.gwt.server.ApplicationServlet</servlet-class>
<init-param>
<description>Vaadin application class to start</description>
<param-name>application</param-name>
<param-value>scalaadin.ScalaadinApplication</param-value>
</init-param>
<init-param>
<param-name>widgetset</param-name>
<param-value>scalaadin.gwt.CombinedWidgetset</param-value>
</init-param>
</servlet>see also
Authentication: Vaadin + Shiro
Later