新增加了状态栏、菜单栏和工具栏，界面如下：

代码如下：

# -*- coding: utf-8 -*-import sysfrom PyQt4 import QtGui, QtCoreclass Example(QtGui.QMainWindow):    def __init__(self):        #QtGui.QMainWindow.__init__(self)        super(Example, self).__init__()        self.initUI()    def initUI(self):        QtGui.QToolTip.setFont(QtGui.QFont('SansSerif', 10))  # 设置一个用来提示消息的字体，10px字体SansSerif        #定义主体内容        label = QtGui.QLabel('Are you alone?',self)        #label.move(60,60)        label.setStatusTip('Yes or No')        btn = QtGui.QPushButton('Sure', self)        btn.setToolTip('This is a QPushButton widget')        #btn.resize(60,25)        btn.setGeometry(190, 210, 60, 25)        qbtn = QtGui.QPushButton('Quit', self)        #qbtn.resize(60, 25)        qbtn.setGeometry(270, 210, 60, 25)        qbtn.clicked.connect(self.qbtnClick)        self.resize( 350, 250)        self.statusBar().showMessage('Ready')        self.center()        self.setWindowTitle('Test')        self.setWindowIcon(QtGui.QIcon('flat.png'))        exit = QtGui.QAction(QtGui.QIcon('flat.png'), 'Exit', self)        exit.setShortcut('Ctrl+Q')        exit.setStatusTip('Exit Application')        exit.connect(exit, QtCore.SIGNAL('triggered()'), QtGui.qApp, QtCore.SLOT('quit()'))        menubar = self.menuBar()                                                  #创建一个菜单栏        file = menubar.addMenu('&File')                                          #创建一个菜单        file.addAction(exit)                                                      #把动作对象添加到菜单中        toolbar = self.addToolBar('Exit')        toolbar.addAction(exit)    def qbtnClick(self):        reply = QtGui.QMessageBox.question(self, 'Message',                                           'Are you sure to quit?', QtGui.QMessageBox.Yes,                                           QtGui.QMessageBox.No)        if reply == QtGui.QMessageBox.Yes:            quit()    def center(self):        qr = self.frameGeometry()                                       #得到该主窗口的矩形框架qr        cp = QtGui.QDesktopWidget().availableGeometry().center()        #屏幕中间点的坐标cp        qr.moveCenter(cp)                                               #将矩形框架移至屏幕正中央        self.move(qr.topLeft())                                         #应用窗口移至矩形框架的左上角点    def closeEvent(self, event):        reply = QtGui.QMessageBox.question(self, 'Message',                                             'Are you sure to quit?', QtGui.QMessageBox.Yes,                                             QtGui.QMessageBox.No)        if reply == QtGui.QMessageBox.Yes:            event.accept()        else:            event.ignore()def main():    app = QtGui.QApplication(sys.argv)    main = Example()    main.show()    sys.exit(app.exec_())if __name__ == '__main__':    main()