It's my private project. The point is that the minimap, item list, browse field, and item properties, so almost everything they have on that screenshot - are all available on public repositories (there are at least four that developed their features independently). The codebase is ugly and adding small things requires changing over 10 files at a time, but the mapeditor itself gets the job done. Hence why, it wasn't replaced by anything yet.
There was one discussed in the 7.7 files thread, but as far as I'm aware, it was only available as a compiled executable.