function get_width(){
   return (document.body.clientWidth+document.body.scrollLeft);
}
function get_height(){
   return (document.body.clientHeight+document.body.scrollTop);
}
function get_left(w){
   var bw=document.body.clientWidth;
   var bh=document.body.clientHeight;
   w=parseFloat(w);
   return (bw/2-w/2+document.body.scrollLeft);
}
function get_top(h){
   var bw=document.body.clientWidth;
   var bh=document.body.clientHeight;
   h=parseFloat(h);
   return (bh/2-h/2+document.body.scrollTop);
}

// 锁屏
function showScreen(w,top)
{
    var Msg = document.getElementById('Message');
    var Bg = document.getElementById('Screen');
    Bg.style.width = get_width() +'px';
    Bg.style.height = get_height()+'px';
    document.getElementById('Message').style.left=(document.body.clientWidth/2)-w/2; // alert(screen.height/2-240);
    document.getElementById('Message').style.top=top;
    Msg.style.display = 'block';
    Bg.style.display = 'block';
    Bg.style.zIndex=1000;
    Msg.style.zIndex=1001;
}
//解屏
function hideScreen()
{
    var Msg = document.getElementById('Message');
    var Bg = document.getElementById('Screen');
    Msg.style.display = 'none';
    Bg.style.display = 'none';
}

function showDWGSeeDiff()
{
    showScreen(700,200);
}