Deixar um listbox visible ao digitar no RichEdit?

procedure TForm1.sListBoxKeyDown(Sender: TObject; var Key: Word;


  Shift: TShiftState);


var


  i: Integer;


begin


  i := sListBox.ItemIndex;


  if key = 13 then


  begin


    RichEdit1.Text := RichEdit1.Text + ' '+ sListBox.Items[i];


    RichEdit1.Text := RichEdit1.Text + ' ';


    RichEdit1.SetFocus;


    Keybd_Event(VK_END,0,0,0);


    sListBox.Visible := False;


  end;


end;

procedure TForm1.RichEdit1Change(Sender: TObject);


var


  nPos, Linha: Integer;


  sTexto: String;


begin


  With RichEdit1 do


  begin


    SetFocus;


    sTexto := 'casa';


    nPos := FindText(sTexto, 0, Length(RichEdit1.Text), []);


    if nPos >= 0 then


    begin


      sListBox.Visible := True;


      sListBox.ItemIndex := 0;


      sListBox.SetFocus;


    end;


  end;


end;

procedure TForm1.RichEdit1Change(Sender: TObject);
var
  I: Integer;
begin
  for I := 0 to RichEdit1.Lines.Count - 1 do
  begin
    if RichEdit1.Lines.Strings[I] = 'casa' then
    begin
      ListBox1.Visible := True;
      ListBox1.SetFocus;
    end;
  end;

end;

var
Linha:Integer;

procedure TForm6.RichEdit1Change(Sender: TObject);
var
  sTexto: String;
begin
  With RichEdit1 do
  begin
    SetFocus;
    Linha:=Perform(EM_LINEFROMCHAR,SelStart, 0);
    sTexto:=Lines.Strings[Linha];
    sTexto:=copy(sTexto,length(sTexto)-3,4);
    if sTexto = 'casa' then
    begin
      sListBox.Visible := True;
      sListBox.Left:=Left+
                      self.Canvas.TextWidth(Lines.Strings[Linha]);
       sListBox.top:=TOP+
                     (Linha)*Form6.Canvas.TextHeight(Lines.Text);
      sListBox.ItemIndex := 0;
      sListBox.SetFocus;
    end;
  end;
end;

procedure TForm6.sListBoxKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
var
  i: Integer;
  sTexto:String;
begin
  i := sListBox.ItemIndex;
  if key = 13 then
  begin
     with RichEdit1 do
       begin
         SetFocus;
         Lines.Strings[Linha]:= Lines.Strings[Linha]+' '+ sListBox.Items[i]+' ';
         Keybd_Event(VK_END,0,0,0);
         sListBox.Visible := False;
       end;
  end;
end;