Nur in compiz-0.7.6: autom4te.cache.
diff -ur compiz-0.7.6.orign/config.h.in compiz-0.7.6/config.h.in
--- compiz-0.7.6.orign/config.h.in	2008-05-29 14:07:46.000000000 +0200
+++ compiz-0.7.6/config.h.in	2008-10-22 16:31:36.000000000 +0200
@@ -45,6 +45,9 @@
 /* Define to 1 if metacity version >= 2.17.0 */
 #undef HAVE_METACITY_2_17_0
 
+/* Define to 1 if metacity version >= 2.23.2 */
+#undef HAVE_METACITY_2_23_2
+
 /* Define to 1 if you have the <stdint.h> header file. */
 #undef HAVE_STDINT_H
 
diff -ur compiz-0.7.6.orign/configure compiz-0.7.6/configure
--- compiz-0.7.6.orign/configure	2008-05-29 14:07:30.000000000 +0200
+++ compiz-0.7.6/configure	2008-10-17 21:05:36.000000000 +0200
@@ -25047,6 +25047,16 @@
 else
   have_metacity_2_17_0=no
 fi
+      if test -n "$PKG_CONFIG" && \
+    { (echo "$as_me:$LINENO: \$PKG_CONFIG --exists --print-errors \"libmetacity-private >= 2.23.2\"") >&5
+  ($PKG_CONFIG --exists --print-errors "libmetacity-private >= 2.23.2") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; then
+  have_metacity_2_23_2=yes
+else
+  have_metacity_2_23_2=no
+fi
     fi
 
     if test "x$use_gnome" = "xyes"; then
@@ -25270,6 +25280,13 @@
 _ACEOF
 
   fi
+  if test "$have_metacity_2_23_2" = yes; then
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_METACITY_2_23_2 1
+_ACEOF
+
+  fi
 fi
 
  if test "x$use_gnome" = "xyes"; then
diff -ur compiz-0.7.6.orign/configure.ac compiz-0.7.6/configure.ac
--- compiz-0.7.6.orign/configure.ac	2008-05-29 14:05:16.000000000 +0200
+++ compiz-0.7.6/configure.ac	2008-10-17 21:05:10.000000000 +0200
@@ -326,6 +326,8 @@
 		       [have_metacity_2_15_21=yes], [have_metacity_2_15_21=no])
       PKG_CHECK_EXISTS(libmetacity-private >= 2.17.0,
 		       [have_metacity_2_17_0=yes], [have_metacity_2_17_0=no])
+      PKG_CHECK_EXISTS(libmetacity-private >= 2.23.2,
+		       [have_metacity_2_23_2=yes], [have_metacity_2_23_2=no])
     fi
 
     if test "x$use_gnome" = "xyes"; then
@@ -379,6 +381,10 @@
     AC_DEFINE(HAVE_METACITY_2_17_0, 1,
 	      [Define to 1 if metacity version >= 2.17.0])
   fi
+  if test "$have_metacity_2_23_2" = yes; then
+    AC_DEFINE(HAVE_METACITY_2_23_2, 1,
+	      [Define to 1 if metacity version >= 2.23.2])
+  fi
 fi
 
 AM_CONDITIONAL(USE_GNOME, test "x$use_gnome" = "xyes")
diff -ur compiz-0.7.6.orign/gtk/window-decorator/gtk-window-decorator.c compiz-0.7.6/gtk/window-decorator/gtk-window-decorator.c
--- compiz-0.7.6.orign/gtk/window-decorator/gtk-window-decorator.c	2008-05-29 13:58:33.000000000 +0200
+++ compiz-0.7.6/gtk/window-decorator/gtk-window-decorator.c	2008-10-22 16:38:56.000000000 +0200
@@ -5949,11 +5949,17 @@
 
     if (sides[0] != NULL)
     {
-	gboolean used[META_BUTTON_FUNCTION_LAST];
 	char	 **buttons;
 	int	 b;
+	gboolean used[META_BUTTON_FUNCTION_LAST];
 
-	memset (used, 0, sizeof (used));
+	for (i = 0; i < META_BUTTON_FUNCTION_LAST; i++)
+	{
+	   used[i] = FALSE;
+#ifdef HAVE_METACITY_2_23_2
+	   new_layout.left_buttons_has_spacer[i] = FALSE;
+#endif
+        }
 
 	buttons = g_strsplit (sides[0], ",", -1);
 
@@ -5961,54 +5967,90 @@
 	while (buttons[b] != NULL)
 	{
 	    f = meta_button_function_from_string (buttons[b]);
-	    if (f != META_BUTTON_FUNCTION_LAST && !used[f])
-	    {
-		new_layout.left_buttons[i++] = f;
-		used[f] = TRUE;
-
-		f = meta_button_opposite_function (f);
-		if (f != META_BUTTON_FUNCTION_LAST)
-		    new_layout.left_buttons[i++] = f;
-	    }
+#ifdef HAVE_METACITY_2_23_2
+	    if (i > 0 && strcmp("spacer", buttons[b]) == 0)
+            {
+	       new_layout.left_buttons_has_spacer[i - 1] = TRUE;
+	       f = meta_button_opposite_function (f);
+
+	       if (f != META_BUTTON_FUNCTION_LAST)
+                  new_layout.left_buttons_has_spacer[i - 2] = TRUE;
+            }
 	    else
+#endif
 	    {
-		fprintf (stderr, "%s: Ignoring unknown or already-used "
-			 "button name \"%s\"\n", program_name, buttons[b]);
+	       if (f != META_BUTTON_FUNCTION_LAST && !used[f])
+	       {
+                  used[f] = TRUE;
+                  new_layout.left_buttons[i++] = f;
+
+		  f = meta_button_opposite_function (f);
+
+                  if (f != META_BUTTON_FUNCTION_LAST)
+                      new_layout.left_buttons[i++] = f;
+
+	       }
+	       else
+	       {
+		  fprintf (stderr, "%s: Ignoring unknown or already-used "
+			   "button name \"%s\"\n", program_name, buttons[b]);
+	       }
 	    }
-
 	    b++;
 	}
 
+	new_layout.left_buttons[i] = META_BUTTON_FUNCTION_LAST;
+
 	g_strfreev (buttons);
 
 	if (sides[1] != NULL)
 	{
-	    memset (used, 0, sizeof (used));
+	    for (i = 0; i < META_BUTTON_FUNCTION_LAST; i++)
+	    {
+		used[i] = FALSE;
+#ifdef HAVE_METACITY_2_23_2
+		new_layout.right_buttons_has_spacer[i] = FALSE;
+#endif
+	    }
 
 	    buttons = g_strsplit (sides[1], ",", -1);
 
 	    i = b = 0;
 	    while (buttons[b] != NULL)
 	    {
-		f = meta_button_function_from_string (buttons[b]);
-		if (f != META_BUTTON_FUNCTION_LAST && !used[f])
-		{
-		    new_layout.right_buttons[i++] = f;
-		    used[f] = TRUE;
-
-		    f = meta_button_opposite_function (f);
-		    if (f != META_BUTTON_FUNCTION_LAST)
-			new_layout.right_buttons[i++] = f;
-		}
-		else
-		{
-		    fprintf (stderr, "%s: Ignoring unknown or already-used "
-			     "button name \"%s\"\n", program_name, buttons[b]);
-		}
-
-		b++;
+	       f = meta_button_function_from_string (buttons[b]);
+#ifdef HAVE_METACITY_2_23_2
+	       if (i > 0 && strcmp("spacer", buttons[b]) == 0)
+	       {
+		  new_layout.right_buttons_has_spacer[i - 1] = TRUE;
+		  f = meta_button_opposite_function (f);
+		  if (f != META_BUTTON_FUNCTION_LAST)
+		     new_layout.right_buttons_has_spacer[i - 2] = TRUE;
+	       }
+	       else
+#endif
+	       {
+		   if (f != META_BUTTON_FUNCTION_LAST && !used[f])
+		   {
+		       used[f] = TRUE;
+		       new_layout.right_buttons[i++] = f;
+
+		       f = meta_button_opposite_function (f);
+
+		       if (f != META_BUTTON_FUNCTION_LAST)
+			   new_layout.right_buttons[i++] = f;
+		   }
+		   else
+		   {
+		       fprintf (stderr, "%s: Ignoring unknown or "
+				"already-used button name \"%s\"\n",
+				program_name, buttons[b]);
+		   }
+	       }
+	       b++;
 	    }
-
+	    new_layout.right_buttons[i] = META_BUTTON_FUNCTION_LAST;
+	    
 	    g_strfreev (buttons);
 	}
     }