什么叫可拖动的？试着这样的吗
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title> New Document </title>
<meta name="Generator" content="EditPlus">
<meta name="Author" content="">
<meta name="Keywords" content="">
<meta name="Description" content="">
<SCRIPT LANGUAGE="JavaScript">
<!--
function chooseCigBrand(){ showx = (screen.width - 405 )/2;
showy = (screen.height - 342 )/2;
var rsValue = window.showModalDialog("a.html", "", "dialogWidth:405px; dialogHeight:342px; dialogLeft:"+showx+"px; dialogTop:"+showy+"px; status:no; directories:yes;scrollbars:no;Resizable=no; " );}//-->
</SCRIPT>
</head><body>
<INPUT type="button" value="弹出页面" onclick="chooseCigBrand();return false;" style="cursor:hand;" >
</body>
</html>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<html>
<head>
<title> New Document </title>
<meta name="Generator" content="EditPlus">
<meta name="Author" content="">
<meta name="Keywords" content="">
<meta name="Description" content="">
<SCRIPT LANGUAGE="JavaScript">
<!--
function chooseCigBrand(){ showx = (screen.width - 405 )/2;
showy = (screen.height - 342 )/2;
var rsValue = window.showModalDialog("a.html", "", "dialogWidth:405px; dialogHeight:342px; dialogLeft:"+showx+"px; dialogTop:"+showy+"px; status:no; directories:yes;scrollbars:no;Resizable=no; " );}//-->
</SCRIPT>
</head><body>
<INPUT type="button" value="弹出页面" onclick="chooseCigBrand();return false;" style="cursor:hand;" >
</body>
</html>
{ MaskDiv()
var createDiv = document.createElement("div");
createDiv.setAttribute("id","loginDiv");
createDiv.style.position="absolute";
createDiv.style.width="243px";
createDiv.style.height="200px";
createDiv.style.zIndex="55555666";
//createDiv.style.backgroundColor="#000000";
createDiv.style.display="block";
createDiv.style.borderBottomWidth="1px";
createDiv.style.borderBottomColor="#0066CC";
//createDiv.style.backgroundColor="#999999";
document.body.appendChild(createDiv); //alert("ww")
var bodyh= screen.availHeight;
var bodyw=document.body.clientWidth;
var objw=createDiv.clientWidth;
var objh=createDiv.clientHeight; createDiv.style.left= (bodyw-objw)/2;
//DivRecom.style.top = (bodyh-objh)/2;
createDiv.style.top=(bodyh-objh)/4;
//创建登陆层头部
var HeadDiv=document.createElement("div");
HeadDiv.style.height="30px";
HeadDiv.style.width="100%";
HeadDiv.style.backgroundColor="#0066CC";
HeadDiv.style.borderBottom="1px solid #666666";
/*
HeadDiv.onmousedown=Milan_StartMove(event,'loginDiv');
HeadDiv.onmouseup=Milan_StopMove(event,'loginDiv');
HeadDiv.style.cursor="move";
*/
HeadDiv.style.fontSize="14px";
HeadDiv.style.color="#ffffff";
HeadDiv.style.fontWeight="bold";
HeadDiv.style.lineHeight="30px";
HeadDiv.innerHTML="用户登录";
HeadDiv.style.textAlign="center";
createDiv.appendChild(HeadDiv);
//创建内容层
var CountentDiv=document.createElement("div");
CountentDiv.style.height="170px";
CountentDiv.style.width="100%";
CountentDiv.setAttribute("id","loginDivCont");
CountentDiv.style.backgroundColor="#ffffff";
CountentDiv.style.color="#000";
//HeadCountent.style.borderBottom="1px solid #666666";
createDiv.appendChild(CountentDiv);
var str;
//str="<form name='form1' method='post' action='Login.aspx?name=textfieid.values'>";
/*
str+="<table width='100%' height='22' border='0' cellpadding='0' cellspacing='0' style='font-size:12px;'><tr>"
str+="<td align='center' bgcolor='#999999'>用户登录</td></tr></table>"
*/str="<table width='243' height='' border='0' align='center' cellpadding='0' cellspacing='0' style='font-size:12px;'>"
str+=" <tr> <td width='70' height='30' align='right' valign='bottom'>用户名：</td><td width='173' valign='bottom'><input type='text' size='11'style='with:30px' id='textfield' name='textfield'></td></tr>";
str+=" <tr><td align='right' height='30' valign='bottom'>密码：</td><td width='173' valign='bottom'><input type='password' size='13' style='with:30px' id='textfield2' name='textfield2'></td></tr>";
str+="<tr><td align='right' height='30'>验证码：</td><td height='30'><input type='text' size='5' id='verifyCode'><img src='AjaxImage.aspx' /></td></tr>";
str+="<tr><td valign='bottom'align='right' height='30'> ";
str+="</td><td valign='bottom'><label><input type='button' name='Submit' onclick='submitAjax()' value='登陆'> <input name='Submit2' type='button' onClick='hidden();'value='取消'>";
str+="</label></td></tr></table>";
document.getElementById("loginDivCont").innerHTML=str;}//创建遮罩层
function MaskDiv()
{
var createMask=document.createElement("div");
createMask.style.position="absolute";
createMask.style.backgroundColor="#000";
createMask.style.left="0px";
createMask.style.width= "100%";
createMask.setAttribute("id","MaskDiv");
createMask.style.top="0px";
createMask.style.height= screen.availHeight;
createMask.style.filter="alpha(opacity=60)";
createMask.style.zIndex="55555665";
document.body.appendChild(createMask);
}
//取消触发函数，隐藏相关层
function hidden()
{
document.getElementById("MaskDiv").style.display='none';
document.getElementById("loginDiv").style.display='none';
}
var http_requestDiv=false;这个代码 本来 是AJax动态登录的
包括 遮罩层 看能否对你有帮助！！