public override DataTemplate SelectTemplate(object item, DependencyObject container)
        {
            if ((item as ComboBoxItem).IsSelected)
                return ClosedTemplate;
            else
                return OpenedTemplate;
        }

public class SuggestTemplateSelector : DataTemplateSelector
    {
        public DataTemplate OpenedTemplate { get; set; }
        public DataTemplate ClosedTemplate { get; set; }

        public override DataTemplate SelectTemplate(object item, DependencyObject container)
        {
            if ((container as ContentPresenter).TemplatedParent is ComboBox)
                return ClosedTemplate;
            else
                return OpenedTemplate;
        }
    }

public class DetailsTemplateSelector : DataTemplateSelector
{
    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        var parent = ((FrameworkElement)container).TemplatedParent;
        if (parent is ComboBox)
            return ((ComboBox)parent).FindResource("Closed") as DataTemplate;
        else if (parent is ComboBoxItem)
            return ((ComboBoxItem)parent).FindResource("Opened") as DataTemplate;
        return null;
    }
}

            DataTemplate dataTemplate = new DataTemplate();
            dataTemplate.DataType = typeof(SuggestedAttributeValueInfo);
            Binding binding = new Binding();
            binding.Path = new PropertyPath("Unit");

            FrameworkElementFactory textElement = new FrameworkElementFactory(typeof(TextBlock));
            textElement.SetBinding(TextBlock.TextProperty, binding);

            dataTemplate.VisualTree = textElement;
            return dataTemplate;

            DataTemplate dataTemplate = new DataTemplate();
            dataTemplate.DataType = typeof(SuggestedAttributeValueInfo);
            Binding binding1 = new Binding();
            binding1.Path = new PropertyPath("Unit");

            Binding binding2 = new Binding();
            binding2.Path = new PropertyPath("Count");

            MultiBinding mb = new MultiBinding();
            mb.StringFormat = "{0} [{1}]";
            mb.Bindings.Add(binding1);
            mb.Bindings.Add(binding2);

            FrameworkElementFactory textElement = new FrameworkElementFactory(typeof(TextBlock));
            textElement.SetBinding(TextBlock.TextProperty, mb);

            dataTemplate.VisualTree = textElement;
            return dataTemplate;