Issues when attaching and detaching external app from QDockWidget
I found part of the issue wrt to closing. So when you are creating the self._window in the attach function and you close the MainWindow, that other window (thread) is sitting around still. So if you add a self._window = None in the __init__ function and add a __del__ function as below, that part is fixed. Still not sure about the lack of menu. I'd also recommend holding onto the subprocess handle with self.__p instead of just letting that go. Include that in the __del__ as well.
def __del__(self): self.__p.terminate() if self._window: print('terminating window') self._window.closeProbably better yet would be to include a closeEvent
def closeEvent(self, event): print('Closing time') self.__p.terminate() if self._window is not None: print('terminating window') self._window.close