PyQt application works fine, but when I close it Python shows this message: "Object::connect: No such signal QObject::dataChanged(QModelIndex,QModelIndex)" What is the cause of this? There isn't dataChanged signal in the program.

EDIT: Almost minimal program which causes error:

import sys
from PyQt4.QtCore import *
from PyQt4.QtGui import *
from PyQt4.QtSql import *
import ui_DBMainWindow

global Mw, Table, Tv
Id, Name, Size = range(3)

class TTable():
    pass

Table = TTable()

class TMainWindow(QMainWindow, ui_DBMainWindow.Ui_MainWindow):

    def __init__(self, parent = None):
        global Table
        QMainWindow.__init__(self, parent)
        self.setupUi(self)
        self.showMaximized()
        self.mapper = QDataWidgetMapper(self)
        self.mapper.setModel(Table.Model)

def main():
    global Mw, Table, Tv
    QApp = QApplication(sys.argv)
    DB = QSqlDatabase.addDatabase("QSQLITE")
    DB.setDatabaseName("1.db")
    Table.Model = QSqlTableModel()
    Table.Model.setTable("MainTable")
    Table.Model.select()
    Mw = TMainWindow()
    QApp.exec_()

if __name__ == "__main__":
    main()