前：

1  
     
      2             
      3             
      4 5         
     

后：

1         private void TextBox_SelectionChanged(object sender, RoutedEventArgs e)2         {3             TextBox textBox = sender as TextBox;4             txtStatus.Text = "Selection starts at character #" + textBox.SelectionStart + Environment.NewLine;5             txtStatus.Text += "Selection is " + textBox.SelectionLength + " character(s) long" + Environment.NewLine;6             txtStatus.Text += "Selected text: '" + textBox.SelectedText + "'";7         }