private void cb_Checked(object sender, RoutedEventArgs e)
{
//if (all.IsChecked.Value)
// return;
//bool allck = true;
//foreach (var cb in checkboxes)
//{
// if (cb.IsChecked == false)
// allck = false;
//}
//all.IsChecked = allck;
}
private void cb_Unchecked(object sender, RoutedEventArgs e)