화면의 왼쪽 위로 Form을 옮겨 버리면 간단하지만, 지금 소개하는 방법은
Region API 함수를 사용하는것 입니다.

procedure TForm1.Button1Click(Sender: TObject);
var
  frmRegion, tempRegion: HRGN;
  i: Integer;
  Arect: TRect;
Begin
  frmRegion := 0;
  for I:= 0 to ControlCount - 1 Do
     begin
       aRect := Controls[i].BoundsRect;
       OffsetRect( aRect, clientorigin.x - left, clientorigin.y - top );
       tempRegion := CreateRectRgnIndirect( aRect );
       if frmRegion = 0 Then
          frm Region := tempRegion
       else
          begin
             CombineRgn( frmRegion, frmRegion, tempRegion, RGN_OR );
             DeleteObject( tempRegion );
          end;
     end;

  CombineRgn( frmRegion, frmRegion, tempRegion, RGN_OR );
  SetWindowRgn( handle, frmRegion, True );
  DeleteObject( tempRegion );
end;

즐푸하세염... ^^;;