wpf ActualWidth為0解決方法

LocalNewsControl()
{
    var descriptor = DependencyPropertyDescriptor.FromProperty(ActualWidthProperty, typeof(TextBlock));
    if (descriptor != null)
        descriptor.AddValueChanged(myTextBlock, ActualWidth_ValueChanged);
}

private void ActualWidth_ValueChanged(object a_sender, EventArgs a_e)
{
   //Modify you scroll things here
   ...
}