WE RECOMMEND EVERYONE UPDATES AS SOON AS POSSIBLE!
The update includes all previous 1.4 updates and requires no schema
update (if you upgrade within the 1.4 release).
The fixed security problems are grave, if you have directories writable
by the webserver in you docroot (in most windows server the complete
docroot writable by default, but many linux servers are also set up that
way).
The new version 2.6 of FCKeditor supports now newer Safari and Opera
browsers, see http://www.fckeditor.net
Please note: as FCK contains many static javascript and css files, you
and your users might have to delete the browser cache after the update!
