Refresh bug in "Classic" style dialogs on Vista

Not sure if this is the right group to post to, so please copy/forward as
needed.

If you switch the view settings to "Classic" style (Not Aero), there's a
dialog bug with buttons not refreshing properly. To reproduce:

1. Create a dialog with a dropdown-box and a button immediately below the
dropdown-box. It's important that the dropdown-box cover up the button when
it is openeed.
2. Add a handler for the dropdown-box so that when an item is selected, the
button is disabled. (The button is enabled when the dialog is initially
opened.)
3. Run the app and open the dialog and select and item in the dialog and
the button won't gray out, but the handler told it to gray out.
4. Move another window over the dialog (causing a paint message) and you'll
notice that the button will gray out properly.

There may be other controls that have this same problem, but we just looked
at it with the button.

I have a simple MFC dialog app that shows this, if needed.

James