Hopefully now all calls to escape() are replaced with ajaxEscape() in response to Tomasz's forum post; remove deprecated version of show_category_info() from functions.php
// UK lang variables
tinyMCE.addToLang('',{
insert_advhr_desc : 'Horizontale rule',
insert_advhr_width : 'Width',
insert_advhr_size : 'Height',
insert_advhr_noshade : 'No shadow'
});