Source:

http://bugs.gentoo.org/attachment.cgi?id=184839&action=view

diff -ur guile-gtk-2.0.orig/gtk-gl/gdk-gl.defs guile-gtk-2.0/gtk-gl/gdk-gl.defs
--- guile-gtk-2.0.orig/gtk-gl/gdk-gl.defs	2006-12-09 02:23:15.000000000 +0100
+++ guile-gtk-2.0/gtk-gl/gdk-gl.defs	2009-03-12 22:46:52.000000000 +0100
@@ -22,14 +22,14 @@
 ;--- Types ... --------------------------------------------------------
 
 (define-struct GdkGLContext
-  (copy gdk_gl_context_ref)
-  (free gdk_gl_context_unref)
+  (copy g_object_ref)
+  (free g_object_unref)
   (size "0")
   (canonical-name "Gdk" "GL" "Context"))
 
 (define-struct GdkGLPixmap
-  (copy gdk_gl_pixmap_ref)
-  (free gdk_gl_pixmap_unref)
+  (copy g_object_ref)
+  (free g_object_unref)
   (size "0")
   (canonical-name "Gdk" "GL" "Pixmap"))
 
diff -ur guile-gtk-2.0.orig/gtk-gl/gdk-gl-glue.c guile-gtk-2.0/gtk-gl/gdk-gl-glue.c
--- guile-gtk-2.0.orig/gtk-gl/gdk-gl-glue.c	2006-12-22 10:31:01.000000000 +0100
+++ guile-gtk-2.0/gtk-gl/gdk-gl-glue.c	2009-03-12 22:44:24.000000000 +0100
@@ -83,8 +83,8 @@
 
 sgtk_boxed_info sgtk_gdk_gl_context_info = {
   { "GdkGLContext", GTK_TYPE_BOXED, NULL },
-  (void *(*)(void*))gdk_gl_context_ref,
-  (void (*)(void*))gdk_gl_context_unref,
+  (void *(*)(void*))g_object_ref,
+  (void (*)(void*))g_object_unref,
   (void (*)(SCM)) NULL,
   0
 };
@@ -100,8 +100,8 @@
 
 sgtk_boxed_info sgtk_gdk_gl_pixmap_info = {
   { "GdkGLPixmap", GTK_TYPE_BOXED, NULL },
-  (void *(*)(void*))gdk_gl_pixmap_ref,
-  (void (*)(void*))gdk_gl_pixmap_unref,
+  (void *(*)(void*))g_object_ref,
+  (void (*)(void*))g_object_unref,
   (void (*)(SCM)) NULL,
   0
 };