#837 – A Window Cannot Be a Child of a ContentControl

The content of a ContentControl can be just about anything, including either UI elements or simple CLR objects.  For example, the content of a CheckBox can be something more than a simple text string.

One of the few elements that cannot be used as content for a ContentControl is a Window.  It wouldn’t make sense to place a Window element as the content of something else, like a Button.  A Window can only be the topmost element of the logical tree.

If you do try to include a Window as a child of another element, you’ll get an exception at run-time, when the XAML is parsed.

    <Button Height="23" Width="80">
        <Window Title="A window in a button?" />
    </Button>