Qt MVF custom editor troubles

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

"""Trying to implement a simple custom editor for Qt's MV-framework.
Problems:
The editor (MyButtonEdit) does not update model data on focus out event, when placed
on a form and mapped to QDataWidgetMapper. It works fine in QTableView though.
"""

import sys

from PySide import QtGui, QtCore
from PySide.QtCore import Qt


class EmbeddedButton(QtGui.QToolButton):

    def __init__(self, parent, text, icon=None, slot=None, shortcut=None, tooltip=None):
        super().__init__(parent)
        self.setCursor(QtCore.Qt.ArrowCursor)
        self.setFocusPolicy(Qt.NoFocus)
        self.setText(text)

        if slot:
            self.clicked.connect(slot)
        if shortcut:
            self.setShortcut(shortcut)
        if tooltip:
            self.setToolTip(tooltip)

class ButtonEdit(QtGui.QWidget):

    def __init__(self, parent=None):
        super().__init__(parent)
        layout = QtGui.QHBoxLayout()
        layout.setContentsMargins(0, 0, 0, 0)
        layout.setSpacing(0)

        self.setLayout(layout)
        self.line_edit = QtGui.QLineEdit(self)

        self.text = self.line_edit.text
        self.setText = self.line_edit.setText

        self.layout().addWidget(self.line_edit)
        self.buttons = {}
        self.setFocusProxy(self.line_edit)
        self.line_edit.installEventFilter(self)

    def eventFilter(self, target, event):
        if target == self.line_edit:
            if event.type() == QtCore.QEvent.KeyPress:
                if event.key() == Qt.Key_Tab:
                    self.keyPressEvent(event)
                    return True
            elif event.type() == QtCore.QEvent.FocusOut:
                self.focusOutEvent(event)
                #can not return True - the imput cursor will duplicate.
                # And the data will not be updated anyway.
        return False


    def addButton(self, id, text, icon=None, slot=None, shortcut=None, tooltip=None):
        button = EmbeddedButton(self, text, icon, slot, shortcut, tooltip)
        self.layout().addWidget(button)
        self.buttons[id] = button


class MyButtonEdit(ButtonEdit):
    def __init__(self, parent=None):
        super().__init__(parent)
        self.addButton('first', '1')
        self.addButton('second','2')
        self.addButton('third','3')


class MyDelegate(QtGui.QStyledItemDelegate):

    def __init__(self, parent):
        QtGui.QStyledItemDelegate.__init__(self, parent)

    def createEditor(self, parent, option, index):
        editor = MyButtonEdit(parent)
        editor.setAutoFillBackground(True)
        editor.installEventFilter(self)
        return editor

    def updateEditorGeometry(self, editor, option, index):
        editor.setGeometry(option.rect)

    def setEditorData(self, editor, index):
        editor.line_edit.setText(index.model().data(index, Qt.EditRole))

    def setModelData(self, editor, model, index):
        model.setData(index, editor.line_edit.text())


class MyModel(QtCore.QAbstractTableModel):

    class Person:
        def __init__(self, f_name, l_name):
            self.f_name = f_name
            self.l_name = l_name

    def __init__(self, parent):
        super().__init__(parent)
        self.rows = [MyModel.Person('Joe', 'Smith'), MyModel.Person('Mary', 'Dow')]
        self.columns = ['f_name', 'l_name']

    def columnCount(self, index):
        return len(self.columns)

    def rowCount(self, index):
        return len(self.rows)

    def flags(self, index):
        Qt = QtCore.Qt
        if index.isValid():
            return Qt.ItemIsSelectable | Qt.ItemIsEnabled | Qt.ItemIsEditable

    def data(self, index, role):
        if role == QtCore.Qt.EditRole or role == QtCore.Qt.DisplayRole:
            attr_name = self.columns[index.column()]
            person = self.rows[index.row()]
            return getattr(person, attr_name)

    def setData(self, index, value, role=Qt.EditRole):
        if index.isValid() and role == Qt.EditRole:
            field_name = self.columns[index.column()]
            row = self.rows[index.row()]
            setattr(row, field_name, value)
            self.dataChanged.emit(index, index)
            return True


class MyWin(QtGui.QDialog):

    def __init__(self):
        super().__init__()
        model = MyModel(self)

        mapper = QtGui.QDataWidgetMapper(self)
        mapper.setSubmitPolicy(QtGui.QDataWidgetMapper.AutoSubmit)
        mapper.setModel(model)
        mapper.setItemDelegate(MyDelegate(self))

        lay = QtGui.QVBoxLayout(self)

        table_view = QtGui.QTableView(self)
        table_view.setModel(model)
        table_view.setItemDelegateForColumn(0, MyDelegate(self))
        table_view.setItemDelegateForColumn(1, MyDelegate(self))

        ed_f_name = MyButtonEdit(self)
        ed_l_name = MyButtonEdit(self)

        lay.addWidget(table_view)
        lay.addWidget(ed_f_name)
        lay.addWidget(ed_l_name)

        mapper.addMapping(ed_f_name, 0)
        mapper.addMapping(ed_l_name, 1)
        mapper.toFirst()


if __name__ == '__main__':
    app = QtGui.QApplication(sys.argv)
    win = MyWin()
    win.show()
    sys.exit(app.exec_())