procedure WMGetMinMaxInfo(var mes: TWMGetMinMaxInfo); message WM_GetMinMaxInfo;


procedure TfrmMain.WMGetMinMaxInfo(var mes: TWMGetMinMaxInfo);
var
  I: Integer;
  R: TRect;
begin
  R := Self.Monitor.WorkareaRect;
  mes.MinMaxInfo.ptMaxSize.X := R.Right - R.Left;
  mes.MinMaxInfo.ptMaxSize.Y := R.Bottom - R.Top;
  mes.Result := 0;
  inherited;
end;