function LinesVisible(Memo: TMemo): integer;
  Var
  OldFont : HFont;
  Hand : THandle;
  TM : TTextMetric;
  Rect : TRect;
  tempint : integer;
  begin
  Hand := GetDC(Memo.Handle);
  try
  OldFont := SelectObject(Hand, Memo.Font.Handle);
  try
  GetTextMetrics(Hand, TM);
  Memo.Perform(EM_GETRECT, 0, longint(@Rect));
  tempint := (Rect.Bottom - Rect.) div
  (TM.tmHeight + TM.tmExternalLeading);
  finally
  SelectObject(Hand, OldFont);
  end;
  finally
  ReleaseDC(Memo.Handle, Hand);
  end;
  Result := tempint;
  end;