hyperlink layout bug?

I'm developing a really simple control which is basically just a hyperlink that displays DatePicker in Popup when clicked (all created in code, but I think it doesn't matter). XAML:

<Window x:Class="WpfPopupTest.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"><Grid Name="grid"><TextBlock VerticalAlignment="Center" Name="outerTextBlock" /></Grid></Window>

and the code-behind for it:

public partial class MainWindow : Window {
        private DatePicker datePicker = new DatePicker();
        private Popup popup = new Popup();
        private Hyperlink hyperlink = new Hyperlink();
        public MainWindow() {
            InitializeComponent();
            popup.Child = datePicker;
            popup.Placement = PlacementMode.Relative;
            popup.PlacementTarget = outerTextBlock;
            popup.StaysOpen = false;
            hyperlink.Click += (o, e) => popup.IsOpen = true;
            TextBlock innerTextBlock = new TextBlock { Text = "Click" };
            datePicker.SelectedDateChanged += (o, e) => {
                popup.IsOpen = false;
                innerTextBlock.Text = datePicker.SelectedDate.Value.ToLongDateString();
            };
            hyperlink.Inlines.Add(innerTextBlock);
            outerTextBlock.Inlines.Add(hyperlink);
        }
    }

Consider the following scenario:

- click the hyperlink, popup is open

- click the calendar

- pick date

- popup is closed, selected date is shown as hyperlink text

- the hyperlink becomes non-clickable, the cursor no longer changes to "hand" when the mouse pointer is over it.

But if I move the pointer out of the bounds of this window and return it back or maximize/minimize it or move the window any other way everything becomes fine again. Looks like some kind of call to UpdateLayout is not occuring for my case. Am i missing something?