There are implementations for loading maps made in Tiled and LDTK.
I have no plans to add a room editor to GMEdit myself (that鈥檚 a lot of work! And I鈥檓 not even fully up-to-date on existing GMEdit features), but GMEdit is both open-source and has plugin support that can be used to implement new editors. If you鈥檙e feeling adventurous, you can use this as a starting point.
