dcpomatic2_cli and dcpomatic2_create commands already have a --config command line option to set directory to load config files from.

Would it be possible to add the same option to dcpomatic2 command, to launch the GUI with it using a specified config?

Main reason I ask is that I often worry when switching between stable and test versions of DCP-o-matic, that the test version may alter the config file in some way, so that it then doesn't work when I switch back to stable version. So it'd be nice to be able to run the test version "sandboxed" with its own config.

At present, this doesn't seem to be the case, but in the past there have been times when opening a new version of DCP-o-matic does alter the config (when a bug was found in generation of certificates, for example).

There could be other use cases where you want to set certain preferences on a project-by-project command-by-command basis.