Quote Originally Posted by amleto View Post
mainwindow is only available to gui app.
OK, let me be more clear : "The OP didn't specify if the external app he wants to start is a console app or not." If the external app is a console app, the QProcess approach will work.

And on Windows it IS possible to start an external app and make it appear inside another application. This requires some code in the external app though. But the OP is working on MacOS, and I don't know anything about that.