Liferay: How to change location of VAADIN folder

Hello everyone,

I changed the location of the VAADIN directory into my portlet folder. I overrided the “getStaticFilesLocation” method like this:

    protected String getStaticFilesLocation(PortletRequest request) {
        return request.getContextPath();

This works sometimes. The problem is that I have to reload the site several times until the widgetset and themes are loaded.
Has anyone an idea why this happens?