XSearch is an extended search plugin, that provides a replacement for the built-in jEdit search/replace dialogs. It has awareness of the ProjectViewer plugin, and can restrict its search to the project file set. It uses uses gnu.regexp, an older, unsupported, regular expression library, as an alternative to Sun's java.util.regex. Each has its own quirks and a slightly different syntax, so keep that in mind when doing regex search/replace.