将FontFamily应用于Silverlight 4 Beta中的所有控件

public static class FontFamily
{
    public const string Arial = "Arial";
    public const string TimesNewRoman = "Times New Roman";
    public const string Verdana = "Verdana";
}

   <ResourceDictionary>
       <Style TargetType="TextBlock">
           <Setter Property="FontFamily" Value="FontFamily.Arial" />
        </Style>
       <Style TargetType="TextBox">
           <Setter Property="FontFamily" Value="FontFamily.Verdana" />
        </Style>
       <Style TargetType="Button">
           <Setter Property="FontFamily" Value="FontFamily.TimesNewRoman" />
        </Style>
    </ResourceDictionary>
</Application.Resources>

public MainWindow()
{
    InitializeComponent();

    foreach (var control in this.GetVisualDescendants().OfType<Control>())
    {
        control.FontFamily = new FontFamily(FontFamily.Arial);
    }
}

private IEnumerable<DependencyObject> GetVisualDescendants(DependencyObject root = null)
{
    if (root == null)
    {
        root = this;
    }

    int count = VisualTreeHelper.GetChildrenCount(root);
    for (int i = 0; i< count; i++)
    {
        var child = VisualTreeHelper.GetChild(root, i);
        yield return child;

        foreach (var descendant in GetVisualDescendants(child))
        {
            yield return descendant;
        }
    }
}