hi Thoralf, i'm not a GEM master but if you want a functional oscilloscope, i would recommend you give [fiddle~] a try. it will output a wider and richer amount of data than [snapshot~]. i use it all the time and it's acid.
r
% evol~~~~~~ http://www.mego.at/evol.html
% alku~~~~~~ http://personal.ilimit.es/principio
% imbécil~~~ http://imbecil.net
% foofoofoo~ http://openserver.cccb.org/~foofoofoo