The following example uses the capDriverGetCaps macro to determine whether a capture driver has overlay capabilities; if it does, the macro enables the overlay.
CAPDRIVERCAPS CapDrvCaps;
capDriverGetCaps(hWndC, &CapDrvCaps, sizeof (CAPDRIVERCAPS));
if (CapDrvCaps.fHasOverlay)
capOverlay(hWndC, TRUE);