[ecfisa]

Hola jsc.

Empezado por jsc

...
Si es cierto que puede llegar al final y no haber leído nada, ...

Si, eso es lo primero que pensé ... igual te pongo un ejemplo de una de las formas en que podrías implementarlo:

Código Delphi [-]
...
type
  TForm1 = class( TForm )
    RichEdit1: TRichEdit;
    Button1: TButton;
    procedure FormCreate( Sender: TObject );  
    procedure RichEdit1KeyDown( Sender: TObject; var Key: Word;Shift: TShiftState );
    procedure FormDestroy( Sender: TObject );
  private
    FOldWndProc : TWndMethod;
    procedure FNewWndProc( var Message: TMessage );
    procedure ReachedEnd( const Reach: Boolean );
  public
  end;

var
  Form1: TForm1;

implementation 

procedure TForm1.FormCreate( Sender: TObject );
begin
  RichEdit1.Lines.LoadFromFile('SomeFile.rtf');
  FOldWndProc := RichEdit1.WindowProc;
  RichEdit1.WindowProc := FNewWndProc;
end;

procedure TForm1.ReachedEnd(const Reach: Boolean);
const
  FLAGS =  MB_ICONQUESTION or MB_YESNO; 
  CMSG  = '¿ Seguro que comprende el texto ?';
begin
  if not Reach then
    Exit;
  if MessageBox( Handle,PChar(CMSG), '', FLAGS ) = IDNO then
    Application.Terminate;
  {
   ...
   ...
  }
end;

procedure TForm1.FNewWndProc( var Message: TMessage );
var
  sPos: Integer;
  sInfo: TScrollInfo;
begin
  if Message.Msg = WM_VSCROLL then
  begin
    sInfo.cbSize  := SizeOf( TScrollInfo );
    sInfo.fMask   := SIF_ALL;
    GetScrollInfo( RichEdit1.Handle, SB_VERT, sInfo );
    sPos := GetScrollPos( RichEdit1.Handle, SB_VERT );
    ReachedEnd( ( sInfo.nMax = sInfo.Npage + sPos ) );
  end;
  FOldWndProc(Message);
end;

procedure TForm1.RichEdit1KeyDown( Sender: TObject; var Key: Word; Shift: TShiftState );
var
  RE : TRichEdit;
  Row: Integer;
begin
  if ( Key in [ VK_DOWN, VK_NEXT ] ) then
  begin
    RE  := TRichEdit( Sender );
    Row := RE.Perform( EM_LINEFROMCHAR, RE.SelStart, 0 );
    ReachedEnd( ( Row = RE.Lines.Count - 1 ) );
  end;
end;

procedure TForm1.FormDestroy( Sender: TObjec t);
begin
  RichEdit1.WindowProc := FOldWndProc;
end;

end.

Saludos