I installed the latest version of MonoDevelop (so I could get the latest version of NuGet, so I could get the latest version of Json.NET). MonoDevelop runs as a Flatpak app.
The problem I'm having is that Flatpak's sandboxed approach seems to prevent MonoDevelop from reading my mounted partitions. I also tried to create symbolic links from my home directory to the mounts, but it appears Flatpak doesn't follow symbolic links. I'm running Ubuntu MATE 16.04 on x86_64.
So I'm a bit stuck and wonder if it's just something dumb on my part (wouldn't be the first time). Has anyone had a similar experience or have any workarounds to suggest?
Sry to answer my own question, but I'll post here in case anyone else wonders. I got this answer on twitter (I'll keep his id private).
It sounds like MonoDevelop needs extra permissions to access your filesystem (Flatpak defaults to being restrictive). You can use the flatpak override command described here to give it the specific access you need: https://docs.flatpak.org/en/latest/working-with-the-sandbox.html#overriding-sandbox-permissions
So I used:
flatpak run --filesystem=host com.xamarin.MonoDevelop
and that worked.
Twitter guy also said, if you use:
flatpak override --filesystem=host com.xamarin.MonoDevelop
... it will make the change permanent for your installation, so you don't have to call it that way every time.