//参数-url表示要打开的网站，winname表示打开后的窗体名称
//参数windth表示打开窗体的宽度，height表示打开窗体的高度
function openwindow( url,winName,width,height) 
{
    xposition=0; yposition=0;
    if ((parseInt(navigator.appVersion) >= 4 ))
    {
    xposition = (screen.width - width) / 2;     //窗体居中的x坐标
    yposition = (screen.height - height) / 2;   //窗体居中的y坐标
    }
    theproperty= "width=" + width + ","         //打开窗口的属性
    + "height=" + height + "," 
    + "location=0," 
    + "menubar=0,"
    + "resizable=0,"
    + "scrollbars=0,"
    + "status=0," 
    + "titlebar=0,"
    + "toolbar=0,"
    + "hotkeys=0,"
    + "screenx=" + xposition + "," //仅适用于Netscape
    + "screeny=" + yposition + "," //仅适用于Netscape
    + "left=" + xposition + "," //IE
    + "top=" + yposition; //IE 
    window.open( url,winName,theproperty );     //打开窗口
}