WPF

[System.Windows.Data.ValueConversion(typeof(int), typeof(bool))]
public class SelectedIndexToIsEnabledConverter : System.Windows.Data.IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        return ((int)value >= 0) ? true : false;
    }

    public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        throw new System.NotImplementedException();
    }
}

    <UserControl.Resources >
        <local:SelectedIndexToIsEnabledConverter x:Key="SelectedIndexToIsEnabledConverter" />
    </UserControl.Resources>
...

Example binding:
    IsEnabled="{Binding Path=SelectedIndex,ElementName=comboBox1,Converter={StaticResource SelectedIndexToIsEnabledConverter},Mode=OneWay}" 

Mark Salsbery
Microsoft MVP - Visual C++

modified on Friday, July 15, 2011 12:33 PM