Application.HookMainWindow(AppHook)(zt)

type 
  TMainForm = class(TForm)  
    procedure FormCreate(Sender: TObject) ;  
    procedure FormDestroy(Sender: TObject) ;  
  private 
    function AppHook(var msg: TMessage): boolean;  
  end;  
 
implementation 
 
procedure TMainForm.FormCreate(Sender: TObject) ;  
begin 
  Application.HookMainWindow(AppHook) ;  
end;  
 
 
function TMainForm.AppHook(var msg: TMessage): boolean;  
begin 
  result := false;  
  if (msg.Msg = WM_SYSCOMMAND) and (msg.WParam = SC_RESTORE) then 
    result := MessageDlg('Are you an Admin?', mtWarning, mbYesNo, 0) = mrNo;  
end;  
 
procedure TMainForm.FormDestroy(Sender: TObject) ;  
begin 
  Application.UnhookMainWindow(AppHook) ;  
end; 
type
  TMainForm = class(TForm)
    procedure FormCreate(Sender: TObject) ;
    procedure FormDestroy(Sender: TObject) ;
  private
    function AppHook(var msg: TMessage): boolean;
  end;

implementation

procedure TMainForm.FormCreate(Sender: TObject) ;
begin
  Application.HookMainWindow(AppHook) ;
end;

function TMainForm.AppHook(var msg: TMessage): boolean;
begin
  result := false;
  if (msg.Msg = WM_SYSCOMMAND) and (msg.WParam = SC_RESTORE) then
    result := MessageDlg('Are you an Admin?', mtWarning, mbYesNo, 0) = mrNo;
end;

procedure TMainForm.FormDestroy(Sender: TObject) ;
begin
  Application.UnhookMainWindow(AppHook) ;
end;

重载WndProc不能截取SC_RESTORE，用自定义消息(WM_SYSCOMMAND)也不能截取。