function ShowMessageBox()
{
    var div_mb = document.getElementById("messagebox");
    if(div_mb.style.display != "block")
    {
        div_mb.style.display = "block";
        div_mb.style.left = (document.documentElement.clientWidth - div_mb.offsetWidth) / 2;
        div_mb.style.top = (document.documentElement.offsetHeight - div_mb.offsetHeight) / 2;
        
        document.body.onscroll = function()
        {
            var div_mb = document.getElementById("messagebox");
            div_mb.style.top = (document.documentElement.offsetHeight - div_mb.offsetHeight) / 2 + document.documentElement.scrollTop;
            div_mb.style.left = (document.documentElement.offsetWidth - div_mb.offsetWidth) / 2 + document.documentElement.scrollLeft;
        }
        document.body.onresize = function()
        {
            var div_mb = document.getElementById("messagebox");
            div_mb.style.top = (document.documentElement.offsetHeight - div_mb.offsetHeight) / 2;
            div_mb.style.left = (document.documentElement.offsetWidth - div_mb.offsetWidth) / 2;
        }
    }
    else
    {
        div_mb.style.display = "none";
        document.body.onscroll = function(){void(0);}
        document.body.onresize = function(){void(0);}
    }
}
function ShowValidateImage()
{
    var imgobj = document.getElementById("validateimage");
        imgobj.src = "Login.aspx?v=" + new Date().getSeconds();
        imgobj.style.display = "";
    
}
function FormSubmit()
{
    if(document.forms[0].title.value.replace(/^\s+|\s+$/g,"") == "" && document.forms[0].content.value.replace(/^\s+|\s+$/g,"") == "")
    {
        alert("主题 和 内容不能都为空");
        document.forms[0].content.focus();
        return false;
    }
    if(document.forms[0].validate.value.replace(/^\s+|\s+$/g,"") == "")
    {
        alert("请填写验证码");
        document.forms[0].validate.focus();
        return false;
    }
    document.forms[0].submitok.disabled = true;
}