I typically compose letters, documents, and other things I turn into
PDFs with a text editor and convert them at the terminal using Make.
Once I've converted them to a PDF, I then open them using "atril
FILE-NAME &" from the shell so I can view them while I continue to work
on them using the command line.

However, atril prints a message like the following when I do so:

  (atril:454002): EggSMClient-WARNING **: 21:15:31.545: Failed to connect to the session manager: Could not open network socket

Such messages are unwanted because they clutter up my terminal and
interfere with the prompt and other running programs.  I've in the past
asked GTK+ and its appurtenant libraries to avoid printing
non-user-caused warnings to the console by default, but they've chosen
not to, instead preferring to have individual programs address these
issues, so I'm filing a bug report here.

Note that I am running MATE and have mate-session running, and my
sessions are correctly saved with the session manager, so I believe the
message to be generally in error.  In any event, Atril is fully
functional (and I'm otherwise happy with the way it works), so I don't
think a diagnostic is needed here.