Compile scss file in the widgetset


I am using an addon on my application, which uses an styles.scss file inside the jar.
in the addon jar, the widgetset file has the following line:

but in the jar there’s only (fofo.scss), and when I compile my application widgetset, the compiler says:

Addon styles found from classpath:
WebContennt/VAADIN/themes/fofo/fofo.scss in jar:file:fofo.jar!/

but it doesn’t generate the (fofo.css)!

Note that I am using (styles.css and not styles.scss) for my application, and when I deploy the application I receive the following error message:

Requested resource
[/VAADIN/widgetsets/] not found from filesystem or through class loader. Add widgetset and/or theme JAR to your classpath or add files to WebContent/VAADIN folder.

I have tried to compile the requested (fofo.scss) and deploy the resulting (fofo.css) manually in the (MyApplicationWidgetSet) folder, this will solve the problem, but (fofo.css) will be deleted upon the next widgetset compilation!
And placing (fofo.css) inside the (theme folder) will not solved the problem since for some reason the servlet is trying to find it in the (MyApplicationWidgetSet) folder.

Why isn’t the GWT compiler compiling (fofo.scss)?
Should I include anything in MyApplicationWidgetSet.gwt.xml?