private void addTeacher_MouseUp(object sender, MouseButtonEventArgs e)
        {
            TeacherAddEdit teacher = new TeacherAddEdit();

            teacher.Owner   = this;
            teacher.Closed += (s, eventarg) =>
            {
                teachers_Initialized(s, eventarg);
            };
            teacher.teacherPreferences.Visibility      = Visibility.Hidden;
            teacher.labelTeacherPreferences.Visibility = Visibility.Hidden;
            teacher.ShowDialog();
        }
        private void editTeacher_MouseUp(object sender, MouseButtonEventArgs e)
        {
            DataRowView row = (DataRowView)teachersGrid.SelectedItem;

            if (row != null)
            {
                int    id      = (int)row["ID"];
                string name    = (string)row["Name"];
                string surname = (string)row["Surname"];
                string title   = (string)row["Title"];
                string email   = (string)row["Email"];
                string phone   = (string)row["Phone"];
                string code    = (string)row["Code"];
                string note    = (string)row["Note"];

                TeacherAddEdit teacher = new TeacherAddEdit();
                teacher.Owner   = this;
                teacher.Closed += (s, eventarg) =>
                {
                    teachers_Initialized(s, eventarg);
                };
                teacher.txtId.Text      = id.ToString();
                teacher.txtName.Text    = name;
                teacher.txtSurname.Text = surname;
                teacher.txtTitle.Text   = title;
                teacher.txtEmail.Text   = email;
                teacher.txtPhone.Text   = phone;
                teacher.txtCode.Text    = code;
                teacher.txtNote.Text    = note;
                teacher.ShowDialog();
            }
            else
            {
                MessageBox.Show("Please select a row to edit!", "Information", MessageBoxButton.OK, MessageBoxImage.Information);
            }
        }