Code review comment for lp:~michihenning/unity-scopes-api/scope-cache-dir

> Following up on this:
>
> > - I'm questioning the wisdom of what I suggested above. It seems that the
> > registry is forced to do a lot more than it should have to
>
> How is this going to work for apps? I expect that applications also will need
> a writable area in the file system somewhere. How do apps find out where they
> can write their files?

https://wiki.ubuntu.com/SecurityTeam/Specifications/ApplicationConfinement but iiuic Qt itself was patched to build the directory based on a few envvars. Imo we should just do the same, afterall the path has to be "prefix + scope_id", and the prefix can be passed as an envvar - it's not like a single process can be both unconfined and leaf-net at the same time.