testcase for silly qt qslider event handling

import sys
from PyQt4 import QtGui, QtCore

class Example(QtGui.QWidget):
    def __init__(self):
        super(Example, self).__init__()

        self.initUI()

    def initUI(self):
        sld = QtGui.QSlider(QtCore.Qt.Horizontal, self)
        sld.setFocusPolicy(QtCore.Qt.NoFocus)
        sld.setGeometry(30, 40, 100, 30)
        sld.setTracking(False)
        sld.valueChanged[int].connect(self.changeValue)

        self.label = QtGui.QLabel(self)
        self.label.setPixmap(QtGui.QPixmap('mute.png'))
        self.label.setGeometry(160, 40, 80, 30)

        self.setGeometry(300, 300, 280, 170)
        self.setWindowTitle('QtGui.QSlider')
        self.show()

    def changeValue(self, value):
        print "changeValue called"
        confirm = QtGui.QMessageBox.question(self, "Save exam?",
                "You have not saved the exam data yet. Do you want to save the exam data before BOOM? All unsaved fields will be erased.",
                QtGui.QMessageBox.Save, QtGui.QMessageBox.Discard, QtGui.QMessageBox.Cancel)
        print "changeValue ended"

def main():
    app = QtGui.QApplication(sys.argv)
    ex = Example()
    sys.exit(app.exec_())

if __name__ == '__main__':
    main()