Need a better way to right this piece of javascript code

 document.onmousedown=selectmouse;
document.onmouseup=new Function("isdrag=false");

Code (markup):

The problem is that in IE, you have to double click the side scrollbar to move it, and the cause is the above code.
The problem only exists when a Proper Valid DocType is set!


The entire code below.

<script type='text/javascript'>
function styledPopupClose(id) {
  document.getElementById(id).style.display = "none";
}
function show_popup(id){
window.parent.document.getElementById(id).style.display="block";
window.parent.document.getElementById("div_id").innerHTML=id;
}
//document.onmousedown=selectmouse;
//document.onmouseup=new Function("isdrag=false");
</script>

Code (markup):

<style type='text/css'>
.dragme { cursor: move }
</style>

Code (markup):

<div id="div_id" style="display:none;"></div>

Code (markup):

<div id='location' name='location' class="change_location" style="display:none;position:absolute;top: 50px;left: 350px">
    <div class="head_change">
    	<img src="/accounts/movablepopups/images/newpopup_location_top.jpg" alt="Click and hold to move me around the page" title="Click and hold to move me around the page" width="370" height="21" class="dragme" />
    </div>
  <div style="width:370px;height:203px;background-image:url(/accounts/movablepopups/images/newpopup_location_bg.jpg);clear:left; position:relative;">
    <form name="searchform1" method="post" action="" onSubmit="return check_data_frame();" style="float:left; width:370px;text-align:center;margin:0px;">
            <div class="grey_12pt" style="width:370px;text-align:center;margin-top:10px;">

            Please enter a new location below and hit the go button
            </div>
            	<div class="grey_12pt_bold"  style="width:370px;text-align:center;margin-top:27px;">
            	WHERE  (e.g. Los Angeles,  90210)</div>
            	<div align="center"> 
                <input name="search_bar_zip" type="text" 
                            class="grey_12pt_bold" id="search_bar_zip" style="width:240px;height:20px" onFocus="this.value=''" onBlur="if (this.value == '') {this.value = '';}" 
                            value="">
                <input name="search_bar_category" type="hidden" class="grey_12pt_bold" id="search_bar_category" style="width:240px;height:20px" value="">
              </div> 
            <div class="grey_10pt" style="margin-top:10px;width:370px;text-align:center;">
            Enter your City or Zip Code here
            </div>

				<div align="center" style="margin-top:8px;">
              <input name="submit" type="image" 
                    src="/../images/latest_search_go.png" width="71" height="45" 
                    border="0">
           		 </div>
      </form>
      <a href='javascript:styledPopupClose("location");' class="links_new">close</a>
      </div>
      <div style="float:left;">
<img src="/accounts/movablepopups/images/newpopup_location_bot.jpg" width="370" height="17" /></div>
</div>

Code (markup):

<a href="#" onClick='return show_popup("location");' style="float:right;color:#fff;font-size:10px;" rel="nofollow" id="change_l">change location</a>

Code (markup):