Add nonce for widget accessibility mode.

Props vortfu.

See #23328.

Merges [39765] to 3.7 branch.

Built from https://develop.svn.wordpress.org/branches/3.7@39771


git-svn-id: http://core.svn.wordpress.org/branches/3.7@39709 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/screen.php

@@ -901,7 +901,8 @@ public function show_screen_options() {
 
 		switch ( $this->id ) {
 			case 'widgets':
-				$this->_screen_settings = '<p><a id="access-on" href="widgets.php?widgets-access=on">' . __('Enable accessibility mode') . '</a><a id="access-off" href="widgets.php?widgets-access=off">' . __('Disable accessibility mode') . "</a></p>\n";
+				$nonce = wp_create_nonce( 'widgets-access' );
+				$this->_screen_settings = '<p><a id="access-on" href="widgets.php?widgets-access=on&_wpnonce=' . urlencode( $nonce ) . '">' . __('Enable accessibility mode') . '</a><a id="access-off" href="widgets.php?widgets-access=off&_wpnonce=' . urlencode( $nonce ) . '">' . __('Disable accessibility mode') . "</a></p>\n";
 				break;
 			default:
 				$this->_screen_settings = '';

wp-admin/widgets.php

@@ -17,6 +17,8 @@
 
 $widgets_access = get_user_setting( 'widgets_access' );
 if ( isset($_GET['widgets-access']) ) {
+	check_admin_referer( 'widgets-access' );
+
 	$widgets_access = 'on' == $_GET['widgets-access'] ? 'on' : 'off';
 	set_user_setting( 'widgets_access', $widgets_access );
 }