Add file to sandbox doesn't work on fuse drives

[willscott]

I've used sshfs to interact with files on a remote file system. I wanted to play a song from VLC, but was unable to make the contents of the mount-point or a sub-folder of the mountpoint visible within the VLC sandbox. Instead, the action fails with a 'can't stat ' warning.

[conorsch]

Also unable to access sshfs-mounted files in vlc. Would be a nice improvement.