请问:怎么在以showModalDialog方式弹出的页面中实现history.go(-1)

以一个例子说明我的问题:(例子很简单,不知道为什么不能history.go(-1),请各位指点,谢谢)
show1.html:
<HTML>
   <HEAD>
        <script>
             function show(){
        showModalDialog("linkH.html","","center:yes;scroll:no;")
    }
</script>
    </HEAD>
    <BODY>
<input type="button" onclick="show()" value="testButton" >
    </BODY>
</HTML>linkH.html:
<html>
    <BODY>
<iframe name="showTar" src="show2.html" style="width:800px;height:600px;">
    </BODY>
</HTML>show2.html:
<BODY>
    <form action="show3.html" target="_self" method="post">
         <table >
     <tr>
<td>aaaaaaaaa</td>
<td>bbbbbbbbb</td>
     </tr>
     <tr>
<td>bbbbbbbbb</td>
<td>bbbbbbbbb</td>
     </tr>
</table>
<input type="submit" name="submitButton">
    </form>
</BODY>show3.html:
<BODY>
     <input type="button" onclick="javascript:history.go(-1)" value="historyGo">
</BODY>