private void butt4_Click(object sender, RoutedEventArgs e)
{
EditSubject subWindow = new EditSubject();
subWindow.Owner = this;
subWindow.Show();
}
private void butt6_Click(object sender, RoutedEventArgs e)
{
var selectItem = (Subject)lstbox_sb.SelectedValue;
EditSubject subWindow = new EditSubject(selectItem);
subWindow.Owner = this;
subWindow.Show();
}