Steve, Waldek, thanks for your messages. I used the diff file to change pop/extern/lib/pop_poll.c
Then in $usepop ran: re-build.sh which went through the usual two phases and then created the standard saved images in $usepop/pop/lib/psv (without motif -- which required an extra step that I forgot to add): clisp.psv pml.psv prolog.psv startup.psv xved.psv So I ran xved (= pop11 +xved) Then (Enter) help rclib which gives a high level overview of what's available. A demo that tests a variety of facilities: teach rc_control_panel That loads a 'teach' file that is also executable. The tutorial bits are all in a long comment, starting at the beginning of the file. All the components (sliders, buttons, menus, etc.) worked as expected. Used this to compile the basic sim_agent library. uses rclib ENTER help rclib Gives a lot of pointers to available facilites. uses simlib compiles the sim_agent library. I then tried a demo that uses sim_agent -- a couple of simple "agents" move toward targets, see each other if close find obstacles, and try to go round them, also showing [simplified] facial expressions (happy, sad, etc.) teach sim_feelings Another tutorial that's an executable file, mostly consisting of a long tutorial comment. The agents try to get to their 'targets', going round obstacles (if they can) and can also be moved by mouse. Some things make them happy, others neural or sad, depending where they are and what's in their neighbourhood. So far everything I've tried worked as expected. I'll look again at popracer later. Aaron