Question: i'm stuck with airspace problem. My WPF app hosts a winform component. I want to display a popup with some "waiting-please" text during component loading and long activities. Here I get my problem: popup is correctly display but when I handle component's busy event I cannot update popup content. Here some code XAML:

```
<WindowsFormsHost Name="wfh" Grid.Row="1" Grid.Column="0" ></WindowsFormsHost>
<Popup x:Name="Overlay" AllowsTransparency="True" Placement="Center" 
       StaysOpen="True"
       IsOpen="True" 
       PlacementTarget="{Binding RelativeSource={RelativeSource FindAncestor,   AncestorType=Grid, AncestorLevel=1}}">
    <TextBlock Name="tbWait"  Foreground="Red" />
</Popup>

```

and c#:

```
myWinformComponent.Event => (s, e) => 
{ 
   tbWait.Text = e.IsBusy ?  "Loading..." : string.Empty;
}

```

I know what is the Airspace problem with WinForm and WPF but I was supposed that keep the popup always open let me display any content ove the windowformshost.

EDIT: I'm placing some breakpoints into the code behind and I see the Text property change correctly. This changes are not display into the UI.

Have you any workaround or solution?
Thank you guys!

Answer: 
According with @HansPassant comment, I can force redraw with these lines:

```
DispatcherFrame frame = new DispatcherFrame();
Dispatcher.CurrentDispatcher.BeginInvoke(DispatcherPriority.Background, new DispatcherOperationCallback(delegate(object parameter) {
        frame.Continue = false;
        return null;
    }), null);
Dispatcher.PushFrame(frame);

```

Maybe it's not the most elegant solution, but it's a working patch to my issue.
Unfortunately, you can't display any WPF content over a WindowsFormsHost. I spent a long time fighting this quirk myself, until I finally gave up and rearraged the UI to make the overlay not have to be over the WinForms component.