delphi xe 10分组按钮CategoryButtons 折叠按钮

设计时界面：

 

代码如下：

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 230
  ClientWidth = 261
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  PixelsPerInch = 96
  TextHeight = 13
  object CategoryButtons1: TCategoryButtons
    Left = 0
    Top = 0
    Width = 105
    Height = 290
    ButtonFlow = cbfVertical
    ButtonOptions = [boFullSize, boGradientFill, boShowCaptions, boVerticalCategoryCaptions]
    Categories = <
      item
        Caption = 'ABC'#37096#38376
        Color = 15395839
        Collapsed = False
        Items = <
          item
            Caption = #20320#22909'ABC'
          end
          item
            Caption = #20320#22909'ABCD'
          end
          item
            Caption = #20320#22909'ABCDE'
          end>
      end
      item
        Caption = 'aoe'#37096#38376
        Color = 16771839
        Collapsed = False
        Items = <
          item
            Caption = 'AB000'
          end
          item
            Caption = 'AB001'
          end
          item
            Caption = 'AB002'
          end
          item
            Caption = 'AB003'
          end>
      end
      item
        Color = 16771818
        Collapsed = False
        Items = <>
      end
      item
        Color = 15400959
        Collapsed = False
        Items = <>
      end>
    DockSite = True
    RegularButtonColor = clWhite
    SelectedButtonColor = 15132390
    TabOrder = 0
  end
end