Following up from #297 (closed).
Meld's current find bar implementation is in an old style that isn't really shared by any other applications. While we have different considerations (specifically multiple related panes), it would be be nice to try to share a design with something else.
Probably the closest design to something that we could use is from the Builder design page: https://wiki.gnome.org/Apps/Builder/SearchAndReplace
However, anything like this would need some prototyping to see how we could integrate it, where the search bar could be packed, etc.