resize the main window so that it is smaller than your form window so it will always hide behind your form.

this is what i do on my main.prg

With _Screen
.Width = 120 && smaller than my form width
.Height = 120 && smaller than my form height
.WindowState = 0
.AutoCenter = .T.
.Show()
Endwith

do form form1

in the moved event add:

_SCREEN.LEFT = THISFORM.LEFT
_SCREEN.TOP = THISFORM.TOP

in config.fpw
SCREEN=OFF

in your form property
desktop=.t.

hope this help.