wpf mvvm具有非依赖属性？

我有一个小(我希望)的问题.我有一个wpf项目,我使用MVVM,但我需要设置文本框的“SelectedText”属性. “selectedText”不是依赖属性,所以我不能使用绑定…
我怎么解决这个问题？ 如果您只需要从VM到控件的值赋值,则可以使用这样的AttachedProperty.

public class AttachedProperties
{
    private static DependencyProperty SelectedTextProperty =
        DependencyProperty.RegisterAttached("SelectedText", typeof(string),
            typeof(AttachedProperties), new PropertyMetadata(default(string), OnSelectedTextChanged)));

     private static void OnSelectedTextChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
     {
         var txtBox = d as TextBox;
         if (txtBox == null)
             return;

         txtBox.SelectedText = e.NewValue.ToString();
     }

     public static string GetSelectedText(DependencyObject dp)
     {
         if (dp == null) throw new ArgumentNullException("dp");

         return (string)dp.GetValue(SelectedTextProperty);
     }

     public static void SetSelectedText(DependencyObject dp, object value)
     {
         if (dp == null) throw new ArgumentNullException("dp");

         dp.SetValue(SelectedTextProperty, value);
     }
}

和用法

<!-- Pls note, that in the Binding the property 'SelectedText' on the VM is refered -->
<TextBox someNs:AttachedProperties.SelectedText="{Binding SelectedText}" />