Minimize semua windows

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
var
   h : HWnd;
begin
     h:=handle;
     while h > 0 do
     begin
          if IsWindowVisible(h) then
             Postmessage(h,WM_SYSCOMMAND,SC_MINIMIZE,0);
          h:=GetnextWindow(h,GW_HWNDNEXT);
     end;
end;