Disable the window mode options for always full-screen renderers

app/streaming/video/ffmpeg-renderers/mmal.h

@@ -16,6 +16,7 @@ public:
     virtual void renderFrame(AVFrame* frame) override;
     virtual enum AVPixelFormat getPreferredPixelFormat(int videoFormat) override;
     virtual bool needsTestFrame() override;
+    virtual int getRendererAttributes() override;
 
 private:
     static void InputPortCallback(MMAL_PORT_T* port, MMAL_BUFFER_HEADER_T* buffer);