Got it--I didn't have openjdk installed. It might be a good idea to mention this in the readme file, as I'm sure there are others out there like me who struggle with the basics.
From: daniel.iglesia@gmail.com
Date: Wed, 27 Apr 2016 08:16:10 -0700
To: pd-list@lists.iem.at
Subject: Re: [PD] mobmuplat editor on Ubuntu
The .jar file should also be double-clickable. Let me know if it isn't on Ubuntu.
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