PROCEDURE TMAINFORM.ClientWndProc(VAR Message: TMessage);
VAR
  MyDC : hDC;
  Ro, Co : Word;
begin
  with Message do
    case Msg of
      WM_ERASEBKGND:
        begin
          MyDC := TWMEraseBkGnd(Message).DC;
          FOR Ro := 0 TO ClientHeight DIV Image1.Picture.Height DO
              FOR Co := 0 TO ClientWIDTH DIV Image1.Picture.Width DO
              BitBlt(MyDC, Co*Image1.Picture.Width, Ro*Image1.Picture.Height,
              Image1.Picture.Width, Image1.Picture.Height,
              Image1.Picture.Bitmap.Canvas.Handle, 0, 0, SRCCOPY);
              Result := 1;
         end;
      else
         Result := CallWindowProc(FPrevClientProc, ClientHandle, Msg, wParam,lParam);
    end;
end;