global_listener_demo.py

import sys
from PySide.QtCore import *
from PySide.QtGui import *


class KeyListener(QObject):
    def eventFilter(self, obj, event):
        if event.type() == QEvent.KeyPress:
            if event.key() == Qt.Key_Control:
                print('Control pressed')
        elif event.type() == QEvent.KeyRelease:
            if event.key() == Qt.Key_Control:
                print('Control released')
        return False


class Window(QMainWindow):
    def keyPressEvent(self, e):
        if e.key() == Qt.Key_O and e.modifiers() & Qt.ControlModifier:
            print('Control+O pressed')
        return super(Window, self).keyPressEvent(e)


def main():
    listener = KeyListener()
    app = QApplication(sys.argv)
    app.installEventFilter(listener)

    win = Window()
    win.show()
    app.exec_()


if __name__ == '__main__':
    main()