Comment 4 for bug 523803

I had this same experience. PDF files were not opening in evince. Desktop is a nomachine client connected to neatx server. Example:

    $ evince
    No protocol specified
    Cannot parse arguments: Cannot open display:
    $

Workaround, in the same terminal as above:

    $ xhost +
    access control disabled, clients can connect from any host
    $

Now evince opens PDF files, e.g. from within Chromium.

Speculation that the xhost command should be added to the NX client's "Run the following command":
E.g
xfce4-session & xhost +

HTH?