如何扩展VCL的hint

unit MyHintWindow;

interface
  uses
    Forms,Windows,Messages,Controls,Themes,Classes,Graphics;

type
  TMyHintWindow = class(THintWindow)
  protected
    procedure NCPaint(DC: HDC); override;
    procedure Paint; override;
  end;

  TMyHintWindowClass = class of TMyHintWindow;

implementation
var
  tempBmp:TBitMap;
  procedure init;
  begin
    tempBmp := TBitmap.Create;
    tempBmp.LoadFromFile(‘Chrysanthemum.bmp‘);
  end;
  { TMyHintWindow }


procedure TMyHintWindow.NCPaint(DC: HDC);
begin
  inherited;
  //在这里写入绘画非客户区的代码
end; 

procedure TMyHintWindow.Paint;
var
  clientRect:TRect;
begin
  Self.Width := 500;
  Self.Height := 500;
  clientRect:= GetClientRect;
  clientRect.Bottom := clientRect.Top + 3;
  Canvas.Brush.Color := clred;
  Canvas.FillRect(clientRect);
  Canvas.Brush.Color := clWhite;
  clientRect:= GetClientRect;
  clientRect.Top := clientRect.Top + 3;
  Canvas.FillRect(clientRect);
  Canvas.TextOut(100,3,Caption);
  Canvas.Draw(0,18,tempBmp);
end;

initialization
  init;
finalization
  tempBmp.Free;
end.

program Project1;

uses
  Forms,
  Unit1 in ‘Unit1.pas‘ {Form1},
  MyHintWindow in ‘MyHintWindow.pas‘;

{$R *.res}

begin
  Application.HintColor := $000000;
  Application.HintHidePause := 10000;
  HintWindowClass := TMyHintWindow;
  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  Application.Run;
end.