CanExpandConverter.cs

using System;
using System.Globalization;
using System.Windows;
using System.Windows.Data;

namespace Common.WPF.Converters
{
    public class CanExpandConverter : IValueConverter
    {
        public object Convert(object obj, Type type, object parameter, CultureInfo culture)
        {
            return (bool)obj ? Visibility.Visible : Visibility.Hidden;
        }

        public object ConvertBack(object obj, Type type, object parameter, CultureInfo culture)
        {
            throw new NotSupportedException();
        }
    }
}