弹出层并锁屏，带模态窗口,后面层变灰

//********* 锁屏DIV ***************************
function LockScreen(tag,title,width,height,url)
{
if (tag) //锁屏
{
var lockdiv = document.getElementById("lockscreen");
if (lockdiv!=null)
{
lockdiv.style.display = "block";
var subdiv = document.getElementById("subdialog");
if (subdiv!=null)
{
subdiv.style.display = "block";
document.getElementById("dialog1").src = url;
}
}else{
//创建新的锁屏DIV,并执行锁屏
var tabframe= document.createElement("div");
tabframe.id = "lockscreen";
tabframe.name = "lockscreen";
tabframe.style.top = '0px';
tabframe.style.left = '0px';
tabframe.style.height = '100%';
tabframe.style.width = '100%';
tabframe.style.position = "absolute";
tabframe.style.filter = "Alpha(opacity=10)";
tabframe.style.backgroundColor="#000000";
tabframe.style.zIndex = "99998";
document.body.appendChild(tabframe);
tabframe.style.display = "block";
//子DIV
var subdiv = document.createElement("div");
subdiv.id = "subdialog";
subdiv.name = "subdialog";
subdiv.style.top = Math.round((tabframe.clientHeight-height)/2);
subdiv.style.left = Math.round((tabframe.clientWidth-width)/2);
subdiv.style.height = height+'px';
subdiv.style.width = width+'px';
subdiv.style.position = "absolute";
subdiv.style.backgroundColor="red";
subdiv.style.zIndex = "99999";
subdiv.style.filter = "Alpha(opacity=100)";
subdiv.style.border = "1px";
subdiv.onmousemove = mouseMoveDialog;
subdiv.onmousedown = control_onmousedown;
subdiv.onmouseup = mouseUp;
document.body.appendChild(subdiv);
subdiv.style.display = "block";
//subdiv.onclick=UNLockScreen;
var iframe_height = height-30;
var titlewidth = width-14;
var html = ""
html += "";
html += "";
html += "";
html += "

	"; html += " "+title+" "; html += "

";
subdiv.innerHTML = html;
}
}else{
//解屏
var lockdiv = document.getElementById("lockscreen");
if (lockdiv!=null)
{
lockdiv.style.display = "none";
}
var subdiv = document.getElementById("subdialog");
if (subdiv!=null)
{
subdiv.style.display = "none";
}
}
}
function UNLockScreen()
{
LockScreen(false);
}

//调用方法

LockScreen(true,"标题",424,314,http://www.baidu.com);