More usable Boolean to Visibility converter for XAML converter

NullableBooleanToVisibilityConverter.cs

public class NullableBooleanToVisibilityConverter : IValueConverter
	{
		/// <summary>
		/// Converts a value. 
		/// </summary>
		/// <returns>
		/// A converted value. If the method returns null, the valid null value is used.
		/// </returns>
		/// <param name="value">The value produced by the binding source.</param>
		/// <param name="targetType">The type of the binding target property.</param>
		/// <param name="parameter">Conditional parameter <c>null</c>, only visible when null. <c>true</c>, only visible when true.</param>
		/// <param name="culture">The culture to use in the converter.</param>
		public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
		{
			//i.e: put parameter as 'true+collapse' says Visible when true, otherwise its collapsed.
			var args = value as bool?;
			var param = parameter.ToString().ToLower();
			if (args == null && param.Contains("null"))
				return Visibility.Visible;
			if (args == true && param.Contains("true"))
				return Visibility.Visible;
			if (args == false && param.Contains("false"))
				return Visibility.Visible;

			return param.Contains("collapse") ? Visibility.Collapsed : Visibility.Hidden;
		}

		/// <summary>
		/// Converts a value. 
		/// </summary>
		/// <returns>
		/// A converted value. If the method returns null, the valid null value is used.
		/// </returns>
		/// <param name="value">The value that is produced by the binding target.</param><param name="targetType">The type to convert to.</param><param name="parameter">The converter parameter to use.</param><param name="culture">The culture to use in the converter.</param>
		public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
		{
			return null;
		}
	}