public boolean isDarkenBehind() {
        return darkenBehind;
    }
Called by SimpleApplication to provide an early font
 so that the fpsText can be created before init.  This
 is because several applications expect to directly access
 fpsText... unfortunately.

@param guiFont the desired font (not null, alias created)
jme3-core/src/main/java/com/jme3/app/StatsAppState.java