Oh wait i see the problem here, it is a *project* file so it isnt handled by gmedit, in which case, im assuming there is no way to override the default dialect without a config.ini? which kind of sucks because i already have a configuration file but its called something completely different, so i would have to make completely empy ini files to make the dialect work.
When a file is opened with or dragged and dropped onto GMEdit, it will first try to open it with existing means (as there’s already a bunch of code for figuring out what to do when you open a .project.gmx vs .object.gmx, for example) and then it’ll go over each installed dialect until it finds one where projectRegex matches the provided path. If nothing matches, it asks Windows to open the file.
For example, Nuclear Throne matches (slightly ambiguously named) main.txt / main.cfg files, but also anything with .ntgml extension.
This is not a perfect system, but it is the only one that allows GMEdit to be set as the app for opening mod files without asking the user for dialect / GM version on open.