diff -r 62a1d3631dcb -r b1b049e28772 MiniDisplay/FutabaVfd.h
--- a/MiniDisplay/FutabaVfd.h	Tue May 27 22:14:29 2014 +0200
+++ b/MiniDisplay/FutabaVfd.h	Wed May 28 08:06:27 2014 +0200
@@ -127,7 +127,7 @@
 	virtual void SetPixel(unsigned char aX, unsigned char aY, bool aOn);
 	virtual void SetAllPixels(unsigned char aPattern);
     virtual int FrameBufferSizeInBytes() const {return KGP12xFrameBufferSizeInBytes;}
-	virtual void BitBlit(BitArray& aBitmap, int aSrcWidth, int aSrcHeight, int aTargetX, int aTargetY) const;
+    virtual void BitBlit(const BitArray& aBitmap, int aSrcWidth, int aSrcHeight, int aTargetX, int aTargetY) const;
 	//From FutabaVfd
 	virtual void SetBrightness(int aBrightness);
 	virtual void Clear();