How can I detect when the cursor leaves a Written Textbox using WPF C#

Question

I have a text box. I want when user type in it as soon as the cursor leaves the text box, some hidden text fields become visible. How can this be done? Thanks.

Answer 1

 private void TextBox_OnLostFocus(object sender, RoutedEventArgs e)
    {
        myControl.Visibility = Visibility.Collapsed;

    }

and in your XAML:

 <TextBox LostFocus="TextBox_OnLostFocus"></TextBox>