=== modified file 'src/dispextern.h'
--- src/dispextern.h	2013-01-02 16:13:04 +0000
+++ src/dispextern.h	2013-03-16 19:55:58 +0000
@@ -3160,6 +3160,14 @@
 
 #ifdef HAVE_WINDOW_SYSTEM
 
+#if defined (HAVE_X_WINDOWS) ||  defined (HAVE_NS)
+#define RGB_PIXEL_COLOR unsigned long
+#endif
+
+#ifdef HAVE_NTGUI
+#define RGB_PIXEL_COLOR COLORREF
+#endif
+
 extern int x_bitmap_height (struct frame *, ptrdiff_t);
 extern int x_bitmap_width (struct frame *, ptrdiff_t);
 extern ptrdiff_t x_bitmap_pixmap (struct frame *, ptrdiff_t);
@@ -3186,7 +3194,7 @@
 void prepare_image_for_display (struct frame *, struct image *);
 ptrdiff_t lookup_image (struct frame *, Lisp_Object);
 
-unsigned long image_background (struct image *, struct frame *,
+RGB_PIXEL_COLOR image_background (struct image *, struct frame *,
                                 XImagePtr_or_DC ximg);
 int image_background_transparent (struct image *, struct frame *,
                                   XImagePtr_or_DC mask);

=== modified file 'src/image.c'
--- src/image.c	2013-03-04 17:35:29 +0000
+++ src/image.c	2013-03-16 19:17:45 +0000
@@ -68,8 +68,6 @@
 #define GET_PIXEL(ximg, x, y) XGetPixel (ximg, x, y)
 #define NO_PIXMAP None
 
-#define RGB_PIXEL_COLOR unsigned long
-
 #define PIX_MASK_RETAIN	0
 #define PIX_MASK_DRAW	1
 #endif /* HAVE_X_WINDOWS */
@@ -88,8 +86,6 @@
 #define GET_PIXEL(ximg, x, y) GetPixel (ximg, x, y)
 #define NO_PIXMAP 0
 
-#define RGB_PIXEL_COLOR COLORREF
-
 #define PIX_MASK_RETAIN	0
 #define PIX_MASK_DRAW	1
 
@@ -110,7 +106,6 @@
 #define GET_PIXEL(ximg, x, y) XGetPixel (ximg, x, y)
 #define NO_PIXMAP 0
 
-#define RGB_PIXEL_COLOR unsigned long
 #define ZPixmap 0
 
 #define PIX_MASK_RETAIN	0