DropDownCount //下拉列表行的数
ItemHeight    //
ItemIndex     //
Items         //
Count         //

procedure TForm1.FormCreate(Sender: TObject);
var
  i: Integer;
begin
  { ComboBox1 }
  for i := 0 to 9 do
    ComboBox1.Items.Add(Format('Item_%d', [i]));
  with ComboBox1 do
  begin
    ItemIndex := 0;
    DropDownCount := 5;
    ListBox.UseSmallScrollBars := True;
    TListBox(ListBox).AlternatingRowBackground := True; //这个兄弟转换用得有点悬, 只是为了让 AlternatingRowBackground 属性暴露出来
  end;

  { ComboEdit1 }
  ComboEdit1.Items.Assign(ComboBox1.Items);
  with ComboEdit1 do
  begin
    ItemIndex := 0;
    DropDownCount := 5;
    ListBox.UseSmallScrollBars := True;
    TListBox(ListBox).AlternatingRowBackground := True;
  end;
//  ComboEdit1.Text := 'Text';
end;