Comment 19 for bug 1643706

Allowing access outside of /home is possible but allowing access to arbitrary places is not possible for obvious reasons. The work on portals is ongoing and it will, for cooperating applications, allow to open files from user-specified locations.

Jamie marked is as Fix Released with precise description of what is allowed. The rest of the work will involve portal integration and it will be released to 18.04 and 16.04 (most likely) and available in most recent versions of other distributions.