function hide_layer(){
    document.getElementById('layer').style.display='none';
}
function show_layer(){
    document.getElementById('layer').style.display='block';
}
function load_layer_page(id){
    var url = '/layer_page.php?id='+id;
    xmlHttp=getAjax(change_page);
    xmlHttp.open('GET', url , true);
    xmlHttp.send(null);
}

function change_page(){
    if (xmlHttp.readyState==4 || xmlHttp.readyState=='complete'){
        document.getElementById('layer_content').innerHTML=xmlHttp.responseText;
    }
}
function getAjax(handler){
    var objXmlHttp=null
    if (navigator.userAgent.indexOf('MSIE')>=0){ 
        var strName='Msxml2.XMLHTTP'
        if (navigator.appVersion.indexOf('MSIE 5.5')>=0){
            strName='Microsoft.XMLHTTP'
        } 
        try { 
            objXmlHttp=new ActiveXObject(strName)
            objXmlHttp.onreadystatechange=handler
            return objXmlHttp
        } catch(e) { 
            alert('Error. Scripting for ActiveX might be disabled') 
            return 
        } 
    } 
    if (navigator.userAgent.indexOf('Mozilla')>=0 || navigator.userAgent.indexOf('Opera')>=0 || navigator.userAgent.indexOf('Safari')>=0)
    {
        objXmlHttp=new XMLHttpRequest()
        objXmlHttp.onload=handler
        objXmlHttp.onerror=handler 
        return objXmlHttp
    }
}