Index: /trunk/Config.kmk
===================================================================
--- /trunk/Config.kmk	(revision 64269)
+++ /trunk/Config.kmk	(revision 64270)
@@ -2379,9 +2379,9 @@
 
  if1of ($(KBUILD_TARGET), freebsd linux solaris)
- # VBOX_PATH_MESA_SOURCE = $(PATH_ROOT)/src/libs/mesa-7.2
-  VBOX_PATH_MESA_SOURCE = $(VBOX_PATH_X11_ROOT)/mesa-7.2
-  VBOX_GL_INCS = \
+  ifndef VBOX_USE_SYSTEM_GL_HEADERS
+   VBOX_GL_INCS = \
         $(VBOX_PATH_X11_ROOT)/glproto-1.4.10 \
         $(VBOX_PATH_X11_ROOT)/mesa-7.2
+  endif
  endif
 
Index: /trunk/src/VBox/Additions/x11/Makefile.kmk
===================================================================
--- /trunk/src/VBox/Additions/x11/Makefile.kmk	(revision 64269)
+++ /trunk/src/VBox/Additions/x11/Makefile.kmk	(revision 64270)
@@ -21,10 +21,16 @@
 if1of ($(KBUILD_TARGET), freebsd linux netbsd openbsd solaris)
  include $(PATH_SUB_CURRENT)/VBoxClient/Makefile.kmk
- include $(PATH_SUB_CURRENT)/vboxvideo/Makefile.kmk
- ifneq ($(KBUILD_TARGET), solaris)
-  include $(PATH_SUB_CURRENT)/vboxmouse/Makefile.kmk
- endif
- ifndef VBOX_USE_SYSTEM_XORG_HEADERS
-  include $(PATH_SUB_CURRENT)/x11stubs/Makefile.kmk
+ ifndef VBOX_NO_LEGACY_XORG_X11
+  include $(PATH_SUB_CURRENT)/vboxvideo/Makefile.kmk
+  ifneq ($(KBUILD_TARGET), solaris)
+   include $(PATH_SUB_CURRENT)/vboxmouse/Makefile.kmk
+  endif
+  # This should logically only be controlled by VBOX_NO_LEGACY_XORG_X11,
+  # as it is not used for drivers at all, but rather to build X11 clients
+  # on systems missing needed libraries.
+  ## @todo fix at some later point when it will not break people's workflows.
+  ifndef VBOX_USE_SYSTEM_XORG_HEADERS
+   include $(PATH_SUB_CURRENT)/x11stubs/Makefile.kmk
+  endif
  endif
 endif