var
Form1: TForm1;
StartButton: hWnd;
OldBitmap: THandle;
NewImage: TPicture;
procedure TForm1.FormCreate(Sender: TObject);
begin
NewImage := TPicture.create;
NewImage.LoadFromFile('C:WindowsCircles.BMP');
StartButton := FindWindowEx(FindWindow('Shell_TrayWnd', nil),0,'Button', nil);
OldBitmap := SendMessage(StartButton, BM_SetImage, 0, NewImage.Bitmap.Handle);
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
SendMessage(StartButton,BM_SetImage,0,OldBitmap);
NewImage.Free;
end;