This version corrects a bug which appeared on a particular Mac. JSesh refused to lauch, displaying the "owl" icon forever. If you haven't problems, you can keep using 2.12.0.
In general, users who experience problems with JSesh are warmly invited to send a mail to the author. Bug reports are very useful for me, and I get very few of them (it might be that JSesh has few bugs, of course :-)).
Oh, still in the mac realm, I have reverted to the old menu system (menus are integrated in the application window, and not in the mac menubar). Older macintoshes (especially those with little memory) have difficulties displaying the hieroglyphic menu when it's a real mac menu. Eventually, I will allow the user to choose between the two menu systems, but for now, I keep using the one which runs well on all machines.