Maximar Form no monitor em uso

 if (frmA7ComparativoVendas.WindowState = wsMaximized) then begin
    frmA7ComparativoVendas.WindowState := wsNormal;
 end else begin
    frmA7ComparativoVendas.WindowState := wsMaximized;
    frmA7ComparativoVendas.SetBounds(0,0,screen.Width,screen.Height-getHeightOfTaskBar);
 end;

function getHeightOfTaskBar : integer;
var hTaskBar:HWND;
    rect : TRect;
begin
  hTaskbar := FindWindow('Shell_TrayWnd', Nil );
  if hTaskBar<>0 then
    GetWindowRect(hTaskBar, rect);
    Result:=rect.bottom - rect.top;
end;