procedure TForm1.PaintBox1Paint(Sender: TObject);
const
  Caption = '?';
var
  TextRect, FocusRect: TRect;
begin
  with TPaintBox(Sender) do
  begin
//    Canvas.Brush.Color := $0075C675;
    Canvas.FillRect(ClientRect);

    TextRect := ClientRect;
    with Canvas.TextExtent(Caption) do
    begin
      TextRect.Top := Height div 2 - cy div 2;
      TextRect.Left := Width div 2 - cx div 2;
    end;
    Canvas.TextRect(TextRect, TextRect.Left, TextRect.Top, Caption);

    FocusRect := ClientRect;
    InflateRect(FocusRect, -1, -1);
    Canvas.DrawFocusRect(FocusRect);
  //  DrawFocusRect(Canvas.Handle, FocusRect);
  end;
end;

    // финт ушами
    Canvas.Pen.Color := clBtnFace;
    Canvas.Brush.Color := clBtnFace;
    Canvas.Font.Color := clWindowText;
    FintRect := ClientRect;
    FintRect.Left := FintRect.Left-1;
    FintRect.Right := FintRect.Left;
    FintRect.Bottom := FintRect.Top;
    Canvas.FillRect(FintRect);

//  + Window.DrawFocusRect вместо Canvas.DrawFocusRect