[ecfisa]

Hola DOS.

Una opción diferente:

Código Delphi [-]
...
type
  TBitBtn = class(Buttons.TBitBtn)
  private
    procedure CMMouseEnter(var M: TMessage); message CM_MOUSEENTER;
    procedure CMMouseLeave(var M: TMessage); message CM_MOUSELEAVE;
  end;

  TForm1 = class(TForm)
    BitBtn_Del_Memo: TBitBtn;
    BitBtn1: TBitBtn;
    BitBtn2: TBitBtn;
    ...
    Memo1: TMemo;
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

...

procedure TBitBtn.CMMouseEnter(var M: TMessage);
var
  WC : TWinControl;
begin
  inherited;
  WC := FindVCLWindow(Mouse.CursorPos);
  if Assigned(WC) and (WC.Name = 'BitBtn_Del_Memo') then
    with Form1.Memo1 do
    begin
      Clear;
      Lines.LoadFromFile(ImagePath12);
    end;
end;

procedure TBitBtn.CMMouseLeave(var M: TMessage);
begin
  inherited;
  Form1.Memo1.Clear;
end;
...

Saludos