function MM_findObj(n, d) { //v4.01
  var p,i,x;  if(!d) d=document; if((p=n.indexOf("?"))>0&&parent.frames.length) {
    d=parent.frames[n.substring(p+1)].document; n=n.substring(0,p);}
  if(!(x=d[n])&&d.all) x=d.all[n]; for (i=0;!x&&i<d.forms.length;i++) x=d.forms[i][n];
  for(i=0;!x&&d.layers&&i<d.layers.length;i++) x=MM_findObj(n,d.layers[i].document);
  if(!x && d.getElementById) x=d.getElementById(n); return x;
}

function showdiv(e) {
    e = e || window.event;
    var cursor = {x:0, y:0};
    if (e.pageX || e.pageY) {
        cursor_x = e.pageX;
        cursor_y = e.pageY;
    } 
    else {
        var de = document.documentElement;
        var b = document.body;
        cursor_x = e.clientX + 
            (de.scrollLeft || b.scrollLeft) - (de.clientLeft || 0);
        cursor_y = e.clientY + 
            (de.scrollTop || b.scrollTop) - (de.clientTop || 0);
    }
	document.getElementById('resultadoletras').style.left=(cursor_x-70) + 'px';
    return cursor;
	
}

function mostrar(nombre,letra){ 
var curleft = curtop = 0;
	obj=document.getElementById(letra);
	if (obj.offsetParent) {
		curleft = obj.offsetLeft
		curtop = obj.offsetTop
		while (obj = obj.offsetParent) {
			curleft += obj.offsetLeft
			curtop += obj.offsetTop
		}
	}
	
	IE='\v'=='v';
	if (IE){
		document.getElementById(nombre).style.top = 219 + 'px';
		document.getElementById(nombre).style.left = (curleft) + 'px';
	}else{
		document.getElementById(nombre).style.top = 203 + 'px';
		document.getElementById(nombre).style.left = (curleft) + 'px';
	}
	document.getElementById(nombre).style.display='block';
} 

function ver(nombre){ 
	document.getElementById(nombre).style.display='block'; 
}
function ocultar(nombre){ 
	document.getElementById(nombre).style.display='none'; 
}

function Ajax(){
        var xmlhttp=false;
        try {
                xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (e) {
                try {
                        xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
                } catch (E) {
                        xmlhttp = false;
                }
        }

        if (!xmlhttp && typeof XMLHttpRequest!='undefined') {
                xmlhttp = new XMLHttpRequest();
        }
        return xmlhttp;
}

function get_marcas(letra, capa) {
	var contenttype = 'application/x-www-form-urlencoded';
	var resultado = document.getElementById(capa);
	var req = Ajax();

	req.open('GET', '_marcas.php?l='+letra, true);
	req.setRequestHeader('Content-Type', contenttype);
	req.onreadystatechange =
		function() {
			if (req.readyState == 4) {
				if(req.responseText!="NULL"){
				resultado.innerHTML = req.responseText;
				mostrar(capa,letra);
				}
			}
		}
	req.send(null);
}