Screen Refresh Problem with WPF

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Hi,
I and my team are currently working on a project where we need to create an
active document server that is hosting a WPF page. We are unsing VS 2008.

We created the active document container as a MFC application that hosts the
WPF page. Everything seems to work fine except the refresh of the WPF page.
E.g. when the active document container is maximized and afterwards the size
is restored sometimes the WPF page is nor drawn, just a gray box is shown.

I tried InvalidateVisual and also
this.Dispatcher.Invoke(System.Windows.Threading.Di spatcherPriority.Loaded,
(NoArgDelegate)delegate { });
to fore a redraw of the WPF page in the OnExitSizeMove of the mfc view
document server but nothing helps.

Does anyone have an idea what else we can do?

Best regards

Olaf