df,

Scrollable forms have exactly the same structure as SDI forms do. In the case of the SDI form, I got bitten by it when trying to control the MSCAL ActiveX control.

Normal In-Screen and In-Top-Level form's (regardless of the Desktop setting) are a single window. Scrollable and SDI forms are more like regular Window's windows. IOW, a frame and a child window. However, they're all based on the same class (in VFP 8.0 SP1 vfp88400000) just different styles and extended styles. I seriously doubt this would create any "hidden" bugs. BTW, this has been true since VFP 6.0 at least and perhaps all the way back to 3.0 (very likely, IMO).