>>Why does it only work with a top level form???
>
>Sorry, don't have an answer for that. Although I would guess it has to do with the way VFP paints forms in the VFP screen.

Roi,
It has nothing to do with VFP. The WS_EX_LAYERED attribute needs to be set on the window for this function to work. Only top-level forms and forms with the Desktop property set to .T. are capable of having this.