怎样用TPaintBox在一个控件上画图，才不会被刷新掉？？

Question

我在Scrollbox上放了Pantbox:执行：
  PaintBox2.Parent:=ZBScScrollBox;
  PaintBox2.Top:=ScIndNameEdit.Top +ScIndNameEdit.Height;
  PaintBox2.Left:=ScIndNameEdit.Left;
  PaintBox2.Width:=ScIndNameEdit.Width;
  PaintBox2.Height:=200;
  PaintBox2.Canvas.Pen.Color:=clRed;
  PaintBox2.Canvas.Pen.Width:=5;
  PaintBox2.Canvas.MoveTo(0,0); 
  PaintBox2.Canvas.LineTo(PaintBox2.Width,0);
  PaintBox2.BringToFront; 却不见显示；
将设PaintBox2.Width:=500；后，有红线，但刷新后就消失了。

Answer 1

应该不能，这是paintbox的特性

Answer 2

paintbox 自己不是有paint事件 嘛
procedure TForm1.PaintBox1Paint(Sender: TObject);
begin
  with Sender as TPaintBox do
  begin
    Height:=200;
    Canvas.Pen.Color:=clRed;
    Canvas.Pen.Width:=5;
    Canvas.MoveTo(0,0);
    Canvas.LineTo(Width,0);
    BringToFront;
  end;
end;