super(DragButton, self).mouseReleaseEvent(event)

def clicked():
    print('click as normal!')
if __name__ == '__main__':
    app = QtGui.QApplication([])
w = QtGui.QWidget()
w.resize(800, 600)
button = DragButton('Drag', w)
button.clicked.connect(clicked)
w.show()
app.exec_()
Dragging/Moving a QPushButton in PyQt