as the demos start up in example - :\pp \gui\tourpython demoall_prg py demodlg demoradio democheck demoscale on some platformsmessages printed by the demo programs (including their own state buttonsmay show up in the original console window where this script is launchedon windowsthe os spawnv call used to start programs by launchmodes in example - completely disconnects the child program' stdout stream from its parentbut the multiprocessing scheme of example - does not regardlessthere is no direct way to call all demosreport methods at once--they are spawned programs in distinct address spacesnot imported modules of coursewe could trigger report methods in the spawned programs with some of the inter-process communication (ipcmechanisms we met in for instancethe demos could be instrumented to catch user signaland could run their report in response the demos could also watch for request strings sent by the launching program to show up in pipes or fifosthe demoall launching program would essentially act as clientand the demo guis as servers that respond to client requests independent programs can also converse this same way over socketsthe general ipc tool introduced in which we'll study in depth in part iv the main window might send report request and receive its result on the same socket (and might even contact demos running remotelyif usedthe multiprocessing module has ipc tools all its ownsuch as the object pipes and queues we studied in that could also be leverageddemos might listen on this type of pipetoo given their event-driven naturegui-based programs like our demos also need to avoid becoming stuck in wait states--they cannot be blocked while waiting for requests on ipc devices like those aboveor they won' be responsive to users (and might not even redraw themselvesbecause of thatthey may also have be augmented with threadstimer-event callbacksnonblocking input callsor some combination of such techniques to periodically check for incoming messages on pipesfifosor sockets as we'll seethe tkinter after method call described near the end of the next is ideal for thisit allows us to register callback to run periodically to check for incoming requests on such ipc tools we'll explore some of these options near the end of after we've looked at gui threading topics but since this is well beyond the scope of the current simple demo programsi'll leave such cross-program extensions up to more parallelminded readers for now running gui code three ways