>I'm obviously missing something here

           .Top = _screen.Top
           .Left = _screen.Left

Here is part of the problem, _screen.Top isn't where I want my preview form to be since it's relative to the VFP screen anyway. .Top = 0 is better. Same goes for .Left.

The problem with doing this is that the code in frxPreviewProxy::Show() won't override the .Top/.Left settings if the resource file has set these to something else.

Here's what it's doing

* Set the form layout based on the resource file (code omitted)

* Check some other things...

otherwise
   WITH THIS.oForm
        if THIS.Top > 0
           .Top = THIS.Top
        endif 
        if THIS.Left > 0
           .Left = THIS.Left
        endif
        * Other code removed

So in the case the resource file has set the preview form's .Top to > 0 and .Left to > 0, and I'm trying to override these settings by setting the proxy objects .Top/.Left to 0, those settings will never be used because it's not > 0.