Hello.

There is a display problem in Japanese, shown by JavaScript function show_popup_menu.

OnClick() display strings passed are processed at CTag::AddAction() in file ctag.inc.php.

PHP function htmlentities() has default charset ISO-8859-1.

By adding charset locale constant S_HTML_CHARSET to htmlentities(), the problem resolved.
It should work both cn and ru.

Below is the small patch.

Sincerely.