'Cell content change'

def setData(self, index, value, role=Qt.EditRole):

    if (not index.isValid()):
        return False
    if (index.column() < 3):
        return False
    value = display_to_value(value, self.get_value(index), ignore_errors=True)
    self.set_value(index, value)
    self.dataChanged.emit(index, index)
    return True
