Merge branch 'MDL-51307-29' of git://github.com/cameron1729/moodle into MOODLE_29_STABLE

lib/outputrenderers.php

@@ -3937,7 +3937,7 @@ EOD;
      * @return string HTML for the header bar.
      */
     public function context_header($headerinfo = null, $headinglevel = 1) {
-        global $DB, $USER;
+        global $DB, $USER, $CFG;
         $context = $this->page->context;
         // Make sure to use the heading if it has been set.
         if (isset($headerinfo['heading'])) {
@@ -3967,7 +3967,7 @@ EOD;
 
             $imagedata = $this->user_picture($user, array('size' => 100));
             // Check to see if we should be displaying a message button.
-            if ($USER->id != $user->id && has_capability('moodle/site:sendmessage', $context)) {
+            if (!empty($CFG->messaging) && $USER->id != $user->id && has_capability('moodle/site:sendmessage', $context)) {
                 $userbuttons = array(
                     'messages' => array(
                         'buttontype' => 'message',