MDI in vista (aero basic)

Sending message WM_MDITILE with the MDITILE_VERTICAL or MDITILE_HORIZONTAL commands does not works. The return code from SendMessage indicates the call was successful but the tiled windows vanish. Their names remain on the Window menu, but the windows are not visible. Sending the WM_MDICASCADE message makes them reappear.

The width and height that Windows passes to the WM_SIZE message appears to have the expected width and height for tiled windows but the windows are not present.

I tried this with several "true" MDI applications (i.e apps that actually use MDI, not just simulate it), such as Eudora 7.0.1 and UltraEdit 12.01a, as well as my own.

I see the same results in all: the tile menus make the open windows disappear and the cascade menu makes them reapear.