Delphi可调整大小的窗体完全删除标题栏

type
  TForm1 = class(TForm)
  private
    procedure WMNCHitTest(var Msg: TWMNCHitTest); message WM_NCHITTEST;
  end;

...

procedure TForm1.WMNCHitTest(var Msg: TWMNCHitTest);
var
  pt: TPoint;
begin
  inherited;
  pt := ScreenToClient(Msg.Pos);
  if pt.X < 5 then
    if pt.Y < 5 then
      Msg.Result := HTTOPLEFT
    else if pt.Y > ClientHeight - 5 then
      Msg.Result := HTBOTTOMLEFT
    else
      Msg.Result := HTLEFT
  else if pt.X > ClientWidth - 5 then
    if pt.Y < 5 then
      Msg.Result := HTTOPRIGHT
    else if pt.Y > ClientHeight - 5 then
      Msg.Result := HTBOTTOMRIGHT
    else
      Msg.Result := HTRIGHT
  else if pt.Y < 5 then
    Msg.Result := HTTOP
  else if pt.Y > ClientHeight - 5 then
    Msg.Result := HTBOTTOM;
end;