class MyProgressBar(QtGui.QProgressBar):
    def __init__(self, parent = None):
        QtGui.QProgressBar.__init__(self, parent)
        self.setStyleSheet(DEFAULT_STYLE)

    def setValue(self, value):
        QtGui.QProgressBar.setValue(self, value)

        if value == self.maximum():
            self.setStyleSheet(COMPLETED_STYLE)