--- a/src/glyphs-x.c	Mon Aug 13 08:53:21 2007 +0200
+++ b/src/glyphs-x.c	Mon Aug 13 08:53:38 2007 +0200
@@ -59,6 +59,9 @@
 
 #include <setjmp.h>
 
+/* Set to 1 if you wish to implement this feature */
+# define HAVE_SUBWINDOWS 0
+
 #define LISP_DEVICE_TO_X_SCREEN(dev)					\
   XDefaultScreenOfDisplay (DEVICE_X_DISPLAY (XDEVICE (dev)))
 
@@ -140,8 +143,10 @@
 	}
       write_c_string (")", printcharfun);
       break;
+#if HAVE_SUBWINDOWS
     case IMAGE_SUBWINDOW:
       /* #### implement me */
+#endif
     default:
       break;
     }
@@ -202,8 +207,10 @@
       if (IMAGE_INSTANCE_X_NPIXELS (p1) != IMAGE_INSTANCE_X_NPIXELS (p2))
 	return 0;
       break;
+#if HAVE_SUBWINDOWS
     case IMAGE_SUBWINDOW:
       /* #### implement me */
+#endif
       break;
     default:
       break;
@@ -221,8 +228,10 @@
     case IMAGE_COLOR_PIXMAP:
     case IMAGE_POINTER:
       return IMAGE_INSTANCE_X_NPIXELS (p);
+#if HAVE_SUBWINDOWS
     case IMAGE_SUBWINDOW:
       /* #### implement me */
+#endif
       return 0;
     default:
       return 0;
@@ -1604,6 +1613,7 @@
   return Qnil;
 }
 
+#if 0
 /* We provide our own version of DGifSlurp() because the standardly
    provided one doesn't handle interlaced GIFs.  This is based on
    code in gif2x11.c. */
@@ -1710,6 +1720,7 @@
 
   return GIF_OK;
 }
+#endif
 
 static void
 gif_instantiate (Lisp_Object image_instance, Lisp_Object instantiator,
@@ -1759,10 +1770,12 @@
 	signal_simple_error ("Unable to decode GIF",
 			     build_string (EmacsPrintGifError ()));
       }
-#if 1
+#if 0
     if (our_own_dgif_slurp_from_gif2x11_c(unwind.giffile) != GIF_OK)
 #else
-      /* DGifSlurp() doesn't handle interlaced files. */
+    /* DGifSlurp() doesn't handle interlaced files. */
+    /* Actually, it does, sort of.  It just sets the Interlace flag 
+       and stores RasterBits in interlaced order.  We handle that below. */
     if (DGifSlurp (unwind.giffile) != GIF_OK)
 #endif
       goto gif_decode_error;
@@ -1801,7 +1814,12 @@
     int width = unwind.giffile->SWidth;
     int depth;
     int bitmap_pad;
-    int i, j;
+    int i, j, row, pass, interlace;
+    /* interlaced gifs have rows in this order:
+       0, 8, 16, ..., 4, 12, 20, ..., 2, 6, 10, ..., 1, 3, 5, ...  */
+    static int InterlacedOffset[] = { 0, 4, 2, 1 };
+    static int InterlacedJumps[] = { 8, 8, 4, 2 };
+
     
     depth = DefaultDepthOfScreen (scr);
     
@@ -1834,14 +1852,35 @@
        optimization routines from XPM (they're in turn mostly
        copied from the Xlib source code). */
     
+    /* Note: We just use the first image in the file and ignore the rest. 
+             We check here that that image covers the full "screen" size.
+	     I don't know whether that's always the case.
+             -dkindred@cs.cmu.edu  */
+    if (unwind.giffile->SavedImages[0].ImageDesc.Height != height
+	|| unwind.giffile->SavedImages[0].ImageDesc.Width != width
+	|| unwind.giffile->SavedImages[0].ImageDesc.Left != 0
+	|| unwind.giffile->SavedImages[0].ImageDesc.Top != 0)
+      signal_simple_error ("First image in GIF file is not full size",
+			   instantiator);
+
+    interlace = unwind.giffile->SavedImages[0].ImageDesc.Interlace;
+    pass = 0;
+    row = interlace ? InterlacedOffset[pass] : 0;
     for (i = 0; i < height; i++)
-      for (j = 0; j < width; j++)
-	XPutPixel (unwind.ximage, j, i,
-		   unwind.pixels[(unsigned char)
-				 /* incorrect signed declaration
-				    of RasterBits[] */
-				 (unwind.giffile->SavedImages->
-				  RasterBits[i * width + j])]);
+      {
+	if (interlace && row >= height)
+	  row = InterlacedOffset[++pass];
+
+	for (j = 0; j < width; j++)
+	  XPutPixel (unwind.ximage, j, row,
+		     unwind.pixels[(unsigned char)
+				  /* incorrect signed declaration
+				     of RasterBits[] */
+				  (unwind.giffile->SavedImages[0].
+				   RasterBits[i * width + j])]);
+
+	row += interlace ? InterlacedJumps[pass] : 1;
+      }
   }
 
   /* 4. Now create the pixmap and set up the image instance */
@@ -3432,6 +3471,7 @@
 }
 
 
+#if HAVE_SUBWINDOWS
 /************************************************************************/
 /*                               subwindows                             */
 /************************************************************************/
@@ -3707,7 +3747,7 @@
 
   return subwindow;
 }
-
+#endif
 
 /************************************************************************/
 /*                            initialization                            */
@@ -3716,6 +3756,7 @@
 void
 syms_of_glyphs_x (void)
 {
+#if HAVE_SUBWINDOWS
   defsymbol (&Qsubwindowp, "subwindowp");
 
   DEFSUBR (Fmake_subwindow);
@@ -3726,6 +3767,7 @@
   DEFSUBR (Fsubwindow_xid);
   DEFSUBR (Fresize_subwindow);
   DEFSUBR (Fforce_subwindow_map);
+#endif
 
   defkeyword (&Q_mask_file, ":mask-file");
   defkeyword (&Q_mask_data, ":mask-data");