diff --git a/configure.in b/configure.in
index dc71a7698..58b88a0b7 100644
--- a/configure.in
+++ b/configure.in
@@ -124,7 +124,7 @@ if test "x$GCC" = "xyes"; then
 fi
 changequote([,])dnl
 
-MUTTER_PC_MODULES='gtk+-2.0 >= 2.20 pango >= 1.2.0'
+MUTTER_PC_MODULES='gtk+-2.0 >= 2.18 pango >= 1.2.0'
 
 AC_ARG_ENABLE(gconf,
   AC_HELP_STRING([--disable-gconf],
@@ -184,8 +184,8 @@ AM_GLIB_GNU_GETTEXT
 # GRegex requires Glib-2.14.0
 PKG_CHECK_MODULES(ALL, glib-2.0 >= 2.14.0)
 # gtk_window_set_icon_name requires gtk2+-2.6.0
-PKG_CHECK_MODULES(MUTTER_MESSAGE, gtk+-2.0 >= 2.20)
-PKG_CHECK_MODULES(MUTTER_WINDOW_DEMO, gtk+-2.0 >= 2.20)
+PKG_CHECK_MODULES(MUTTER_MESSAGE, gtk+-2.0 >= 2.18)
+PKG_CHECK_MODULES(MUTTER_WINDOW_DEMO, gtk+-2.0 >= 2.18)
 
 # Unconditionally use this dir to avoid a circular dep with gnomecc
 GNOME_KEYBINDINGS_KEYSDIR="${datadir}/gnome-control-center/keybindings"
diff --git a/src/Makefile.am b/src/Makefile.am
index a3d892d7d..cc1c3a461 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -39,6 +39,7 @@ mutter_SOURCES= 				\
 	compositor/mutter-shaped-texture.h	\
 	compositor/tidy/tidy-texture-frame.c	\
 	compositor/tidy/tidy-texture-frame.h	\
+	gtk-compat.h				\
 	include/compositor.h			\
 	include/mutter-plugin.h			\
 	include/mutter-window.h			\
diff --git a/src/gtk-compat.h b/src/gtk-compat.h
new file mode 100644
index 000000000..5e029be4f
--- /dev/null
+++ b/src/gtk-compat.h
@@ -0,0 +1,26 @@
+#ifndef __GTK_COMPAT_H__
+#define __GTK_COMPAT_H__
+
+#include <gtk/gtk.h>
+
+/* Provide a compatibility layer for accessor function introduces
+ * in GTK+ 2.20 which we need to build with GSEAL_ENABLE.
+ * That way it is still possible to build with GTK+ 2.18 when not
+ * using GSEAL_ENABLE
+ */
+
+#if !GTK_CHECK_VERSION (2, 20, 0)
+
+#define gtk_widget_get_realized(w) GTK_WIDGET_REALIZED (w)
+#define gtk_widget_get_requisition(w,r) (*r = GTK_WIDGET (w)->requisition)
+#define gtk_widget_set_mapped(w,m)            \
+  G_STMT_START {                              \
+    if (m)                                    \
+      GTK_WIDGET_SET_FLAGS (w, GTK_MAPPED);   \
+    else                                      \
+      GTK_WIDGET_UNSET_FLAGS (w, GTK_MAPPED); \
+  } G_STMT_END
+
+#endif /* GTK_CHECK_VERSION */
+
+#endif /* __GTK_COMPAT_H__ */
diff --git a/src/tools/Makefile.am b/src/tools/Makefile.am
index e9c93abaf..c9a47a7f0 100644
--- a/src/tools/Makefile.am
+++ b/src/tools/Makefile.am
@@ -4,6 +4,7 @@ icondir=$(pkgdatadir)/icons
 icon_DATA=mutter-window-demo.png
 
 INCLUDES=@MUTTER_WINDOW_DEMO_CFLAGS@ @MUTTER_MESSAGE_CFLAGS@ \
+	-I$(top_srcdir)/src \
 	-DMUTTER_ICON_DIR=\"$(pkgdatadir)/icons\" \
 	-DMUTTER_LOCALEDIR=\"$(prefix)/@DATADIRNAME@/locale\"
 
diff --git a/src/tools/mutter-window-demo.c b/src/tools/mutter-window-demo.c
index be5584c84..facc8c985 100644
--- a/src/tools/mutter-window-demo.c
+++ b/src/tools/mutter-window-demo.c
@@ -24,6 +24,8 @@
 #include <X11/Xatom.h>
 #include <unistd.h>
 
+#include "gtk-compat.h"
+
 static GtkWidget* do_appwindow (void);
 
 static gboolean aspect_on;
diff --git a/src/ui/frames.c b/src/ui/frames.c
index 49862a5f2..ba6c81c13 100644
--- a/src/ui/frames.c
+++ b/src/ui/frames.c
@@ -35,6 +35,8 @@
 #include "prefs.h"
 #include "ui.h"
 
+#include "gtk-compat.h"
+
 #ifdef HAVE_SHAPE
 #include <X11/extensions/shape.h>
 #endif
diff --git a/src/ui/metaaccellabel.c b/src/ui/metaaccellabel.c
index cf6e35eab..565f07ca0 100644
--- a/src/ui/metaaccellabel.c
+++ b/src/ui/metaaccellabel.c
@@ -37,6 +37,8 @@
 #include <string.h>
 #include "util.h"
 
+#include "gtk-compat.h"
+
 static void     meta_accel_label_class_init   (MetaAccelLabelClass *klass);
 static void     meta_accel_label_init         (MetaAccelLabel      *accel_label);
 static void     meta_accel_label_destroy      (GtkObject           *object);
diff --git a/src/ui/resizepopup.c b/src/ui/resizepopup.c
index c9e69fcb2..7efbb24f8 100644
--- a/src/ui/resizepopup.c
+++ b/src/ui/resizepopup.c
@@ -26,6 +26,7 @@
 #include "util.h"
 #include <gtk/gtk.h>
 #include <gdk/gdkx.h>
+#include "gtk-compat.h"
 
 struct _MetaResizePopup
 {
diff --git a/src/ui/tabpopup.c b/src/ui/tabpopup.c
index fe4a36c3d..4aa1e984c 100644
--- a/src/ui/tabpopup.c
+++ b/src/ui/tabpopup.c
@@ -36,6 +36,8 @@
 #include <gtk/gtk.h>
 #include <math.h>
 
+#include "gtk-compat.h"
+
 #define OUTSIDE_SELECT_RECT 2
 #define INSIDE_SELECT_RECT 2
 
diff --git a/src/ui/theme.c b/src/ui/theme.c
index 59ff90bfb..3e90f4c4c 100644
--- a/src/ui/theme.c
+++ b/src/ui/theme.c
@@ -62,6 +62,8 @@
 #include <stdlib.h>
 #include <math.h>
 
+#include "gtk-compat.h"
+
 #define GDK_COLOR_RGBA(color)                                           \
                          ((guint32) (0xff                         |     \
                                      (((color).red / 256) << 24)   |    \
diff --git a/src/ui/themewidget.c b/src/ui/themewidget.c
index 05bd839fa..59f91bb99 100644
--- a/src/ui/themewidget.c
+++ b/src/ui/themewidget.c
@@ -24,6 +24,8 @@
 #include "themewidget.h"
 #include <math.h>
 
+#include "gtk-compat.h"
+
 static void meta_area_class_init   (MetaAreaClass  *klass);
 static void meta_area_init         (MetaArea       *area);
 static void meta_area_size_request (GtkWidget      *widget,