-PKG_CHECK_MODULES(LIB, gtk+-2.0 >= $GTK_REQUIRED libgnomeui-2.0 >= $LIBGNOMEUI_REQUIRED)
-PKG_CHECK_MODULES(BACKEND, gtk+-2.0 >= $GTK_REQUIRED gnome-vfs-2.0)
-PKG_CHECK_MODULES(FRONTEND_CORE, gtk+-2.0 >= $GTK_REQUIRED libgnomeui-2.0 >= $LIBGNOMEUI_REQUIRED gnome-icon-theme >= $GNOME_ICON_THEME_REQUIRED libglade-2.0)
-PKG_CHECK_MODULES(SHELL_CORE, gtk+-2.0 >= $GTK_REQUIRED libgnomeui-2.0 >= $LIBGNOMEUI_REQUIRED gnome-vfs-2.0 libglade-2.0 gconf-2.0 gnome-keyring-1 >= $KEYRING_REQUIRED)
+PKG_CHECK_MODULES(LIB, gtk+-2.0 >= $GTK_REQUIRED libgnomeui-2.0 >= $LIBGNOMEUI_REQUIRED libxml-2.0 >= $LIBXML_REQUIRED)
+PKG_CHECK_MODULES(BACKEND, gtk+-2.0 >= $GTK_REQUIRED gnome-vfs-2.0 libgnome-2.0 >= $LIBGNOME_REQUIRED)
+PKG_CHECK_MODULES(FRONTEND_CORE, gtk+-2.0 >= $GTK_REQUIRED libgnomeui-2.0 >= $LIBGNOMEUI_REQUIRED libglade-2.0 gnome-vfs-2.0)
+PKG_CHECK_MODULES(SHELL_CORE, gtk+-2.0 >= $GTK_REQUIRED libgnomeui-2.0 >= $LIBGNOMEUI_REQUIRED gnome-icon-theme >= $GNOME_ICON_THEME_REQUIRED gnome-vfs-2.0 libglade-2.0 gconf-2.0 gnome-keyring-1 >= $KEYRING_REQUIRED)
+
+BACKEND_CFLAGS="$BACKEND_CFLAGS -DGDK_MULTIHEAD_SAFE -DGTK_MULTIHEAD_SAFE"
+AC_SUBST(BACKEND_CFLAGS)