function drag(win) {
    //this.win="";
    var objDiv = document.getElementById(win);
    var isIE = document.all ? true : false; //判断浏览器类型
    document.onmousedown = function (evnt) {//当鼠标左键按下后执行此函数 
        var evnt = evnt ? evnt : event;
        if (evnt.button == (document.all ? 1 : 0)) {
            mouseD = true; //mouseD为鼠标左键状态标志，为true时表示左键被按下 
        }
    }

    objDiv.onmousedown = function (evnt) {
        objDrag = this; //objDrag为拖动的对象 
        var evnt = evnt ? evnt : event;
        if (evnt.button == (document.all ? 1 : 0)) {
            mx = evnt.clientX;
            my = evnt.clientY;
            objDiv.style.left = objDiv.offsetLeft + "px";
            objDiv.style.top = objDiv.offsetTop + "px";
            if (isIE) {
                objDiv.setCapture();
                //objDiv.filters.alpha.opacity = 50;//当鼠标按下后透明度改变 
            } else {
                window.captureEvents(Event.MOUSEMOVE); //捕获鼠标拖动事件 
                //objDiv.style.opacity = 0.5;//当鼠标按下后透明度改变 
            }
        }
    }
    document.onmouseup = function () {
        mouseD = false; //左键松开 
        objDrag = "";
        if (isIE) {
            objDiv.releaseCapture();
            //objDiv.filters.alpha.opacity = 100;//当鼠标左键松开后透明度改变 
        } else {
            window.releaseEvents(objDiv.MOUSEMOVE); //释放鼠标拖动事件 
            //objDiv.style.opacity = 1;//当鼠标左键松开后透明度改变 
        }
    }

    document.onmousemove = function (evnt) {
        var evnt = evnt ? evnt : event;
        if (mouseD == true && objDrag) {
            var mrx = evnt.clientX - mx;
            var mry = evnt.clientY - my;
            objDiv.style.left = parseInt(objDiv.style.left) + mrx + "px";
            objDiv.style.top = parseInt(objDiv.style.top) + mry + "px";
            mx = evnt.clientX;
            my = evnt.clientY;
        }
    }
}