If you look in the toolbox you will find a multi file find
and replace tool. Beware though, it only searches on a single line
in common with many text editors.
To search across multiple lines you need something like FAR
from
http://www.helpware.net
(excellent interface and does much more) or BKReplaceEm (free and
does the job).
Help others by clicking Correct Answer if the question is answered. Found the answer elsewhere? Share it here. "Upvote" is for useful posts.