diff -r fe173cd3652b src/config-store/wscript
--- a/src/config-store/wscript	Fri Aug 19 12:46:14 2011 -0400
+++ b/src/config-store/wscript	Tue Aug 23 12:33:40 2011 -0700
@@ -2,18 +2,58 @@
 
 def configure(conf):
     have_gtk = conf.pkg_check_modules('GTK_CONFIG_STORE', 'gtk+-2.0 >= 2.12', mandatory=False)
-    conf.env['ENABLE_GTK_CONFIG_STORE'] = have_gtk
-    conf.report_optional_feature("GtkConfigStore", "GtkConfigStore",
-                                 conf.env['ENABLE_GTK_CONFIG_STORE'],
-                                 "library 'gtk+-2.0 >= 2.12' not found")
+
+    if have_gtk:
+        # Check that GTK works on the user's machine.
+        fragment = r"""
+#include <gtk/gtk.h>
+int main ()
+{
+  gtk_init (0, 0);
+  return 0;
+}
+"""
+        gtk_works = conf.check(fragment=fragment, msg="Checking that GTK works",
+                               okmsg="complete", errmsg='incomplete',
+                               mandatory=False, uselib="GTK_CONFIG_STORE")
+        conf.report_optional_feature("GtkConfigStore", "GtkConfigStore",
+                                     gtk_works,
+                                     "library 'gtk+-2.0 >= 2.12' found but conf.check failed")
+        conf.env['ENABLE_GTK_CONFIG_STORE'] = gtk_works
+    else:
+        conf.env['ENABLE_GTK_CONFIG_STORE'] = False
+        conf.report_optional_feature("GtkConfigStore", "GtkConfigStore",
+                                     conf.env['ENABLE_GTK_CONFIG_STORE'],
+                                     "library 'gtk+-2.0 >= 2.12' not found")
+
     have_libxml2 = conf.pkg_check_modules('LIBXML2', 'libxml-2.0 >= 2.6', mandatory=False)
+
     if have_libxml2:
         conf.define('HAVE_LIBXML2', 1)
 
-    conf.env['ENABLE_LIBXML2'] = have_libxml2
-    conf.report_optional_feature("XmlIo", "XmlIo",
-                                 conf.env['ENABLE_LIBXML2'],
-                                 "library 'libxml-2.0 >= 2.7' not found")
+        # Check that LIBXML2 works on the user's machine.
+        fragment = r"""
+#include <libxml/xmlunicode.h>
+int main ()
+{
+  int test = xmlUCSIsArabic (0);
+  test *= 1;
+  return 0;
+}
+"""
+        libxml2_works = conf.check(fragment=fragment, msg="Checking that LIBXML2 works",
+                                   okmsg="complete", errmsg='incomplete',
+                                   mandatory=False, uselib="LIBXML2")
+        conf.report_optional_feature("XmlIo", "XmlIo",
+                                     libxml2_works,
+                                     "library 'libxml-2.0 >= 2.6' found but conf.check failed")
+        conf.env['ENABLE_LIBXML2'] = libxml2_works
+    else:
+        conf.env['ENABLE_LIBXML2'] = False
+        conf.report_optional_feature("XmlIo", "XmlIo",
+                                     conf.env['ENABLE_LIBXML2'],
+                                     "library 'libxml-2.0 >= 2.6' not found")
+
     conf.write_config_header('ns3/config-store-config.h', top=True)