}     //SerchByContactVelueTextBox_TextChanged

        private void ChengeContactTextBlock_MouseDown(object sender, MouseButtonEventArgs e)
        {
            if (ContactsDataGrid.SelectedItem is SimpleContact contact)
            {
                AddContactWindow acw = new AddContactWindow(contact);
                if (acw.ShowDialog() == true)
                {
                    Contacts newcont = acw.newContact;
                    if (newcont.contact != contact.contact || newcont.description != contact.description)
                    {
                        try {
                            using (SmallBusinessDBEntities context = new SmallBusinessDBEntities()) {
                                var ppp = context.Contacts.FirstOrDefault(s => s.ContactID == contact.ContactID);

                                ppp.contact     = newcont.contact;
                                ppp.description = newcont.description;

                                context.SaveChanges();
                                MessageBox.Show("Изменения сохранены");

                                contact.contact     = newcont.contact;;
                                contact.description = newcont.description;

                                ContactsDataGrid.Items.Refresh();
                            }
                        }
                        catch (Exception ex) {
                            MessageBox.Show(ex.Message);
                        }
                    } //if
                }     //if
            }         //if
        }