MDL-67544 mod_forum: Add missing label for discussion move

mod/forum/classes/local/renderers/discussion.php

@@ -340,6 +340,9 @@ class discussion {
                 $select = new url_select($forummenu, '',
                         ['/mod/forum/discuss.php?d=' . $discussion->get_id() => get_string("movethisdiscussionto", "forum")],
                         'forummenu', $movebutton);
+                $select->set_label(get_string('movethisdiscussionlabel', 'mod_forum'), [
+                    'class' => 'sr-only',
+                ]);
                 $html .= $this->renderer->render($select);
                 $html .= "</div>";
                 return $html;

mod/forum/lang/en/forum.php

@@ -431,6 +431,7 @@ $string['modulename_link'] = 'mod/forum/view';
 $string['modulenameplural'] = 'Forums';
 $string['more'] = 'more';
 $string['movedmarker'] = '(Moved)';
+$string['movethisdiscussionlabel'] = 'Move the current discussion to the specified forum';
 $string['movethisdiscussionto'] = 'Move this discussion to ...';
 $string['mustprovidediscussionorpost'] = 'You must provide either a discussion id or post id to export';
 $string['myprofileownpost'] = 'My forum posts';