diff --git a/headers/private/servers/app/DisplayDriver.h b/headers/private/servers/app/DisplayDriver.h
index feeada4cec..e4e7a66d9c 100644
--- a/headers/private/servers/app/DisplayDriver.h
+++ b/headers/private/servers/app/DisplayDriver.h
@@ -140,23 +140,23 @@ public:
 	virtual void DrawBitmap(ServerBitmap *bmp, BRect src, BRect dest, LayerData *d);
 	virtual void DrawString(const char *string, int32 length, BPoint pt, LayerData *d, escapement_delta *delta=NULL);
 
-	virtual void FillArc(const BRect r, float angle, float span, RGBColor& color);
-	virtual void FillArc(const BRect r, float angle, float span, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void FillBezier(BPoint *pts, RGBColor& color);
-	virtual void FillBezier(BPoint *pts, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void FillEllipse(BRect r, RGBColor& color);
-	virtual void FillEllipse(BRect r, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void FillPolygon(BPoint *ptlist, int32 numpts, RGBColor& color);
-	virtual void FillPolygon(BPoint *ptlist, int32 numpts, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void FillRect(const BRect r, RGBColor& color);
-	virtual void FillRect(const BRect r, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void FillRegion(BRegion& r, RGBColor& color);
-	virtual void FillRegion(BRegion& r, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void FillRoundRect(BRect r, float xrad, float yrad, RGBColor& color);
-	virtual void FillRoundRect(BRect r, float xrad, float yrad, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
+	virtual void FillArc(const BRect r, float angle, float span, const RGBColor& color);
+	virtual void FillArc(const BRect r, float angle, float span, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void FillBezier(BPoint *pts, const RGBColor& color);
+	virtual void FillBezier(BPoint *pts, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void FillEllipse(BRect r, const RGBColor& color);
+	virtual void FillEllipse(BRect r, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void FillPolygon(BPoint *ptlist, int32 numpts, const RGBColor& color);
+	virtual void FillPolygon(BPoint *ptlist, int32 numpts, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void FillRect(const BRect r, const RGBColor& color);
+	virtual void FillRect(const BRect r, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void FillRegion(BRegion& r, const RGBColor& color);
+	virtual void FillRegion(BRegion& r, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void FillRoundRect(BRect r, float xrad, float yrad, const RGBColor& color);
+	virtual void FillRoundRect(BRect r, float xrad, float yrad, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
 //	virtual void FillShape(SShape *sh, LayerData *d, const Pattern &pat);
-	virtual void FillTriangle(BPoint *pts, RGBColor& color);
-	virtual void FillTriangle(BPoint *pts, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
+	virtual void FillTriangle(BPoint *pts, const RGBColor& color);
+	virtual void FillTriangle(BPoint *pts, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
 
 	virtual void HideCursor(void);
 	virtual bool IsCursorHidden(void);
@@ -166,26 +166,26 @@ public:
 	virtual void ObscureCursor(void);
 	virtual void SetCursor(ServerCursor *cursor);
 
-	virtual void StrokeArc(BRect r, float angle, float span, float pensize, RGBColor& color);
-	virtual void StrokeArc(BRect r, float angle, float span, float pensize, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void StrokeBezier(BPoint *pts, float pensize, RGBColor& color);
-	virtual void StrokeBezier(BPoint *pts, float pensize, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void StrokeEllipse(BRect r, float pensize, RGBColor& color);
-	virtual void StrokeEllipse(BRect r, float pensize, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void StrokeLine(BPoint start, BPoint end, float pensize, RGBColor& color);
-	virtual void StrokeLine(BPoint start, BPoint end, float pensize, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void StrokePoint(BPoint& pt, RGBColor& color);
-	virtual void StrokePolygon(BPoint *ptlist, int32 numpts, float pensize, RGBColor& color, bool is_closed=true);
-	virtual void StrokePolygon(BPoint *ptlist, int32 numpts, float pensize, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color, bool is_closed=true);
-	virtual void StrokeRect(BRect r, float pensize, RGBColor& color);
-	virtual void StrokeRect(BRect r, float pensize, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void StrokeRegion(BRegion& r, float pensize, RGBColor& color);
-	virtual void StrokeRegion(BRegion& r, float pensize, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
-	virtual void StrokeRoundRect(BRect r, float xrad, float yrad, float pensize, RGBColor& color);
-	virtual void StrokeRoundRect(BRect r, float xrad, float yrad, float pensize, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
+	virtual void StrokeArc(BRect r, float angle, float span, float pensize, const RGBColor& color);
+	virtual void StrokeArc(BRect r, float angle, float span, float pensize, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void StrokeBezier(BPoint *pts, float pensize, const RGBColor& color);
+	virtual void StrokeBezier(BPoint *pts, float pensize, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void StrokeEllipse(BRect r, float pensize, const RGBColor& color);
+	virtual void StrokeEllipse(BRect r, float pensize, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void StrokeLine(BPoint start, BPoint end, float pensize, const RGBColor& color);
+	virtual void StrokeLine(BPoint start, BPoint end, float pensize, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void StrokePoint(BPoint& pt, const RGBColor& color);
+	virtual void StrokePolygon(BPoint *ptlist, int32 numpts, float pensize, const RGBColor& color, bool is_closed=true);
+	virtual void StrokePolygon(BPoint *ptlist, int32 numpts, float pensize, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color, bool is_closed=true);
+	virtual void StrokeRect(BRect r, float pensize, const RGBColor& color);
+	virtual void StrokeRect(BRect r, float pensize, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void StrokeRegion(BRegion& r, float pensize, const RGBColor& color);
+	virtual void StrokeRegion(BRegion& r, float pensize, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
+	virtual void StrokeRoundRect(BRect r, float xrad, float yrad, float pensize, const RGBColor& color);
+	virtual void StrokeRoundRect(BRect r, float xrad, float yrad, float pensize, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
 //	virtual void StrokeShape(SShape *sh, LayerData *d, const Pattern &pat);
-	virtual void StrokeTriangle(BPoint *pts, float pensize, RGBColor& color);
-	virtual void StrokeTriangle(BPoint *pts, float pensize, const Pattern& pattern, RGBColor& high_color, RGBColor& low_color);
+	virtual void StrokeTriangle(BPoint *pts, float pensize, const RGBColor& color);
+	virtual void StrokeTriangle(BPoint *pts, float pensize, const Pattern& pattern, const RGBColor& high_color, const RGBColor& low_color);
 
 	virtual void StrokeLineArray(BPoint *pts, int32 numlines, float pensize, RGBColor *colors);