Conversation Search 0.2.0
This little, unobtrusive gem of a plugin adds a "Search in conversations" module to your users messages pages. When they look at their inboxes, they will find a small module which allows searching in conversations. While they are reading a single conversation, they can use the module to search in this very conversation.
Thank @phreak for that fabulous idea!
Search functions are really basic: there is no filtering or sorting option in there. But you can use "+" and "-" for logical AND/NOT searching operations.
Sources are on GitHub