ListBox添加水平进度条

procedure TForm1.Button1Click(Sender: TObject);
var a,bb:integer;
begin

  bb:=0;
  for a:=0 to Listbox1.Items.Count-1 do
  begin
    if bb<listBox1.Canvas.TextWidth(Listbox1.Items[a])  then
    bb:=Listbox1.Canvas.TextWidth(Listbox1.Items[a]);
  end;
  SendMessage(Listbox1.Handle,LB_sethorizontalextent,bb+2,0);  //添加水平滚动条
end;

运行结果如下