Dear all,   after testing Python4Delphi which is, I think, a good bridge/library between these two worlds,  I would like to know if it is right that on standard, the python scripts are running in the main thread of the program, so that the GUI is blocked as long as the python script is running and that there are also no callback (NotifyEvents) available during this time. This is the behavior that I observed. Or is there a switch/paramter on e.g. TPythonEngine so that interprocess GUI communication is available during python script execution?   If communication is only possible when the script execution is running in a seperate thread, what is about TPythonGUIInputOutput and the interprocess communication ? Does it mean that this class as GUI object is always executed in main  thread and therefore it is not threadsafe?   Thanks for your kind answers     Sincerely    Dirk