In todays SVN-build the 'supercon' emulation doesn't work anymore: there's no mousepointer and so this emulation is unusable!
Well, and that's not all: 1) it doesn't know 'newui' anymore, and I can't switch the menubar on/off with <ESC> as in previous versions (can't get this menubar at all now) 2) in fullscreen mode there's no mouse (in any chess emulation)
It seems this M.E.S.S. is becoming more and more a mess, as it is now it's completely unusable! :-(
Just use 0.141 or something earlier as Chess emulation as a whole is getting worked on quite a bit lately. That isn't to dismiss reported error, you'll just be happier as development happens.