Some better security when database is hidden

mod/data/view.php

@@ -81,8 +81,15 @@
         $record = NULL;
     }
 
+
     require_course_login($course, true, $cm);
 
+
+/// If it's hidden then it's don't show anything.  :)
+    if (empty($cm->visible) and !isteacher($course->id)) {
+        notice(get_string("activityiscurrentlyhidden"));
+    }
+
 /// If we have an empty Database then redirect because this page is useless without data
     if (isteacher($course->id)) {
         if (!record_exists('data_fields','dataid',$data->id)) {      // Brand new database!