from PySide import QtCore, QtGui

class TestWidget(QtGui.QWidget):
  """
  A simple Pie menu class. Use in a similar way to QMenu: Create a PieMenu and add QActions to it with QAction.
  """

  def __init__(self, parent=None):
    super(TestWidget, self).__init__(parent)

    # with this flag set the application does not quit properly, without it does
    self.setWindowFlags(QtCore.Qt.Tool)

  def mousePressEvent(self, e):
    self.close() # this closes the widget but does not quit the application
    app = QtGui.QApplication.instance()
    if True: # what logic can I use to figure out if this is a standalone app or run from a host applicatin?
      app.quit()


if __name__ == '__main__':
  import sys
  app = QtGui.QApplication(sys.argv)
  w = TestWidget()
  w.show()
  sys.exit(app.exec_())