MDL-20366 removing the ability to add new activities to invisible sections, I do not think we should encourage this kind of tricks

course/format/topics/format.php

@@ -277,10 +277,6 @@ if ($PAGE->user_is_editing() && has_capability('moodle/course:update', get_conte
         echo '</div>';
         echo '<div class="content">';
         print_section($course, $thissection, $mods, $modnamesused);
-        echo '<br />';
-        if ($PAGE->user_is_editing()) {
-            print_section_add_menus($course, $section, $modnames);
-        }
         echo '</div>';
         echo "</li>\n";
     }

course/format/weeks/format.php

@@ -277,10 +277,6 @@ defined('MOODLE_INTERNAL') || die();
             echo '</div>';
             echo '<div class="content">';
             print_section($course, $thissection, $mods, $modnamesused);
-            echo '<br />';
-            if ($PAGE->user_is_editing()) {
-                print_section_add_menus($course, $section, $modnames);
-            }
             echo '</div>';
             echo "</li>\n";
         }