Force Slide refresh (PowerPoint 2007)

[Pete]

Hi,

I have written a PowerPoint 2007 add-in (although this question could also
apply to a VBA project). The add-in adds a shape to a slide; the new shape is
instantly visible in the preview pane but cannot be seen in the main part of
the PowerPoint window until you move to another slide then move back or until
the application window loses focus. Is there a way to programmatically force
a PowerPoint slide to refresh/repaint?

Thanks,

Pete