如何使用PyQt4禁用窗口最大化图标？

I would like to know how to disable the window Maximise button in pyqt4. I am at present using QWidget.setFixedSize (self, QSize) to prevent user window resizing, however the maximise button is still enabled and when pressed causes the application to move to the top left corner of the screen. I am basically wanting to replicate the behaviour of the Windows calculator application, where the maximise icon is greyed out. Does anyone know how to achieve this with PyQt4? I would like to know how to disable the window