Ctrl+F3一样的查找功能（非弹出窗口）

<script language="javascript">

var iXSFlag=0;//查找匹配标志
var rng;//要查找的整体
function searchTxt()
{
 var backfore = 100000000000000;
 if(rad1.checked)
  backfore = -1;
 else if(rad2.checked)
  backfore = 100000000000000
 if (chkFullMatch.checked == false && chkULMath.checked)
  iXSFlag=4;
 else if (chkFullMatch.checked && chkULMath.checked == false)
  iXSFlag = 2;
 else if (chkFullMatch.checked && chkULMath.checked)
  iXSFlag=6;
 else
  iXSFlag=0;
 if (searchtext.value==null || searchtext.value=='')
 {return;}
 if (rng.findText(searchtext.value,backfore,iXSFlag)==true)
 {
  rng.select();
  rng.scrollIntoView();
  if(rad1.checked)
   rng.moveEnd("character",-1);
  else if(rad2.checked)
   rng.moveStart("character");
 }
 else
 {alert("文档搜索完毕。");}
}
function onKePress()
  {
   rng=document.body.createTextRange();
   if(Trim(searchtext.value)=='')
    btnSerch.disabled=true;
   else
    btnSerch.disabled=false;
  }
  //-->
  </script>

<fieldset style="WIDTH: 100%"><legend>查找</legend>
      <table class="table_text" cellSpacing="0" cellPadding="1" width="100%" border="0">
       <tr>
        <td colSpan="2" height="22">
         <table class="table_text" cellSpacing="0" cellPadding="0" width="100%" border="0">
          <tr>
           <td width="70">&nbsp;查找内容：</td>
           <td><input id="searchtext" οnkeyup="onKePress()" style="WIDTH: 90%" type="text"></td>
           <TD align="right" width="100"><INPUT id="btnSerch" disabled οnclick="searchTxt()" type="button" value="查找下一个"></TD>
          </tr>
         </table>
        </td>
       </tr>
       <tr>
        <td><INPUT id="chkULMath" type="checkbox"><A οnclick="chkULMath.click()" href="#"><font class="table_text" style="POSITION: relative; TOP: -1px">大小写匹配</font></A></td>
        <td vAlign="bottom" rowSpan="2">
         <fieldset><legend>方向</legend><INPUT id="rad1" type="radio" value="0" name="rad"><A οnclick="rad1.click()" href="#"><font class="table_text">向上</font></A> <INPUT id="rad2" type="radio" CHECKED value="1" name="rad"><A οnclick="rad2.click()" href="#"><font class="table_text">向下</font></A></fieldset>
        </td>
       </tr>
       <tr>
        <td><INPUT id="chkFullMatch" type="checkbox"><A οnclick="chkFullMatch.click()" href="#"><font class="table_text" style="POSITION: relative; TOP: -1px">全字匹配</font></A></td>
       </tr>
      </table>
     </fieldset>