基于TImage的自定义组件OnMouseDown事件无法触发问题

我尝试基于TImage创建一个按钮，通过OnMouseDown事件切换两张图片。运行时组件能显示第一张图片，但OnMouseDown事件始终无法触发。我查阅了相关问题但未找到答案，使用Delphi7和Windows11环境。

附上组件代码：

unit ImageBtn;

{$R resources.res resources.rc}

interface

uses WinTypes, WinProcs, Messages, SysUtils, Classes, Controls,
Forms, Graphics, Extctrls, AppEvnts, Buttons;

type

  TImageBtn = class(TImage)
    private
      FCenter : Boolean;
      FDoubleBuffered : Boolean;
      procedure AutoInitialize;
      procedure AutoDestroy;
      procedure SetDoubleBuffered(Value : Boolean);
      procedure WMSize(var Message: TWMSize); message WM_SIZE;

    protected
      procedure Click; override;
      procedure Loaded; override;
      procedure Paint; override;
      procedure MouseDown(Button: TMouseButton; Shift: TShiftState; X, Y: Integer); override;

    public
      constructor Create(AOwner: TComponent); override;
      destructor Destroy; override;

    published
      property OnClick;
      property OnDblClick;
      property OnDragDrop;
      property OnMouseDown;
      property OnMouseMove;
      property OnMouseUp;
      property Center : Boolean read FCenter write FCenter default True;
      property DoubleBuffered : Boolean read FDoubleBuffered write SetDoubleBuffered default True;
      property Height;
      property Proportional default True;
      property Stretch default True;
      property Width;
end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('dcs', [TImageBtn]);
end;

procedure TImageBtn.AutoInitialize;
begin
  FCenter := True;
  FDoubleBuffered := True;
  Height := 29;
  Proportional := True;
  Stretch := True;
  Width := 82;
  Picture.Bitmap.LoadFromResourceName(HInstance,'BITMAP1');
end;

procedure TImageBtn.AutoDestroy;
begin

end;

procedure TImageBtn.MouseDown(Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
begin
  inherited;
  MouseDown(Button, Shift, X, Y);
  Picture.CleanupInstance;
  Picture.Bitmap.LoadFromResourceName(HInstance,'BITMAP2');
end;

procedure TImageBtn.SetDoubleBuffered(Value : Boolean);
begin
  FDoubleBuffered := Value;
end;

procedure TImageBtn.Click;
begin

inherited Click;
end;

constructor TImageBtn.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  AutoInitialize;
end;

destructor TImageBtn.Destroy;
begin
  AutoDestroy;
  inherited Destroy;
end;

procedure TImageBtn.Loaded;
begin
  inherited Loaded;
end;

procedure TImageBtn.Paint;
begin
  inherited Paint;
end;

procedure TImageBtn.WMSize(var Message: TWMSize);
var
  W, H: Integer;
begin
  inherited;
  W := Width;
  H := Height;
  if (W <> Width) or (H <> Height) then
  inherited SetBounds(Left, Top, W, H);
  Message.Result := 0;
end;

end.

编辑补充 #

• 编辑1：无法为OnMouseDown代码添加断点（无蓝色标记点），附上相关截图。
• 编辑2：仅部分代码行有蓝色断点标记，这显然与问题相关。
• 编辑3：感谢各位回复，移除代码中MouseDown(Button, Shift, X, Y);行后问题解决。未使用TBitBtn是因为其边框和对齐方式不符合需求，按钮需要阴影效果。

内容的提问来源于stack exchange，提问作者Learning