Note that there is a subtle difference between adding the handler using Markup View and Design
View if you’re using VB.NET. If you use Markup View, the handler is added to the markup
(OnCheckedChanged="CheckBox1_CheckedChanged") and code is added to the Code Behind.
When you use Design View, the code in Markup View is not affected, and the code in the Code
Behind is annotated with the Handles keyword to indicate which event (for instance, the click on
a button, the check changed event of a check box, and so on) the code responds to. At run time,
however, there is no difference.