monitor the start and end of applications

[awalter1]

Hello,
My purpose is to supervise (from a python program) the launch of some
other programs (python or non python programs) as : "I click on the
button X and the pg X is launched ..."
I want also that my supervision be "wake up" when a pg has exited to
check its status or something like that.
I suppose I need to use thread and I did, I'm trying several solutions
(popen, os.system, commands.getstatusoutput, certainly not correctly) :
generally I am able to launch a pg but when it is ended, the thread
"caller" is still waiting.

Is somebody has encountered similar requirements ?
Thanks a lot for your help