未调用QComboBox的Qt dropEvent

Question

显然，与目前为止所有人都在问这个问题相反，我对拖放并没有意见，只是对QComboBox有意见。QLineEdit工作正常。

以下是相关代码：

class DragDropTextField(QtGui.QLineEdit):
    def __init__(self, title, parent):
        super(DragDropTextField, self).__init__(title, parent)
        self.setAcceptDrops(True)

    def dragEnterEvent(self, e):
        print 'dragEnterEvent'
        e.accept()

    def dropEvent(self, e):
        print 'dropEvent'

class DragDropCombo(QtGui.QComboBox):
    def __init__(self, parent):
        super(DragDropCombo, self).__init__(parent)
        self.setAcceptDrops(True)

    def dragEnterEvent(self, e):
        print 'dragEnterEvent'
        e.accept()

    def dropEvent(self, e):
        print 'dropEvent'