UserControlcontrol is a ContentControl that represents a reusable collection of controls in a predefined layout.
UserControlactually provides very little functionality on top of
ContentControl. The difference is that you will not usually create instances of the
UserControlclass directly; instead a new subclass of the
UserControlclass is usually created for each "view" to be shown by an application. For information on how to create new
UserControlclasses from templates see the quickstart.
The content to display in the control