Maya: A simple qt gui that can be ran within Maya or as standalone (notice the shebang)

guiThingy.py

#!/usr/autodesk/maya/bin/mayapy
import sys

for each in ("PySide", "PySide2"):
    try:
        if each == "PySide2":
            _temp = __import__(each, globals(), locals(), ['QtWidgets'], -1)
            QtWidgets = _temp.QtWidgets
        else:
            _temp = __import__(each, globals(), locals(), ('QtGui'), -1)
            QtWidgets = _temp.QtGui
        _temp = __import__(each, globals(), locals(), ('QtCore'), -1)
        QtCore = _temp.QtCore
        QtGui = QtWidgets
    except ImportError:
        pass
    else:
        break


def mainWindow(widget=None):
    widget = widget or QtGui.QApplication.activeWindow()
    if widget is None:
        return

    parent = widget.parent()
    if parent is None:
        return widget
    return mainWindow(parent)


def isStandAlone():
    return mainWindow() is None


def onClicked(button, label):
    label.setText("Good job!")
    button.setText("Try again ;)")

    button.clicked.connect(button.parent().parent().close)


def main(parent=None):
    win = QtGui.QMainWindow(parent)

    # setup ui
    label = QtGui.QLabel("Hi there, what's up?")
    f = label.font()
    f.setPointSize(16)
    label.setFont(f)

    button = QtGui.QPushButton("Click me!")
    splitter = QtGui.QSplitter(QtCore.Qt.Orientation.Vertical)

    layout = QtGui.QVBoxLayout()
    layout.addWidget(label)
    layout.addWidget(button)
    layout.addWidget(splitter)

    centralWidget = QtGui.QWidget()
    centralWidget.setLayout(layout)

    win.setCentralWidget(centralWidget)

    # manage signal/slots
    button.clicked.connect(lambda: onClicked(button, label))

    return win


if __name__ == '__main__':
    standalone = isStandAlone()
    if standalone:
        app = QtGui.QApplication(sys.argv)

    win = main(mainWindow())
    win.show()

    if standalone:
        sys.exit(app.exec_())