delphi 创建异形窗口[1]

unit Unit1;
interface
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    procedure FormCreate(Sender: TObject);
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  end;
var
  Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.FormCreate(Sender: TObject);
begin
  Button1.Caption := '创建';
  Button2.Caption := '退出';
end;
procedure TForm1.Button1Click(Sender: TObject);
var
  rgn: HRGN;
begin
  rgn := CreateEllipticRgn(0, 0, Width, Height);
  SetWindowRgn(Handle, rgn, True);
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
  Close;
end;
end.