t_login = '<b><u>A</u>cceso de usuarios:</b>';
t_user = document.getElementById('c_user').value; //'Nombre de usuario';
t_pass = document.getElementById('c_pass').value; //'Contraseņa';
document.getElementById('login').innerHTML = '<form name="login" action="login.php" method="post">' + t_login + '<input id="c_user" type="text" value="' + t_user + '" name="user" tabindex="1" accesskey="a"><input id="c_pass" type="text" value="' + t_pass + '" name="pass" tabindex="2"><input type="submit" value="ENTRAR" class="bot_login" tabindex="3"></form>';

function comprobar() {
    c1 = document.getElementById('c_user').value;
    c2 = document.getElementById('c_pass').value;
    if(c1=='' || c1==t_user || c2=='' || c2==t_pass) {
        if(c1=='' || c1==t_user) setTimeout("document.getElementById('c_user').focus()", 50);
        else setTimeout("document.getElementById('c_pass').focus()", 50);
        eventos();
        return false;
    }
    else return true;
}

function eventos() {
    // formulario de LOGIN
    document.getElementById('login').firstChild.onsubmit = comprobar;
    // campo USUARIO //
    c1 = document.getElementById('c_user');
    c1.onfocus = function() { if(c1.value==t_user) c1.value=''; }
    c1.onblur = function() { if(c1.value=='') c1.value=t_user; }

    // campo CONTRASEŅA //
    c2 = document.getElementById('c_pass');
    c2.onfocus = function() {
        if(c2.value==t_pass) {
            us = document.getElementById('c_user').value;
            document.getElementById('login').innerHTML = '<form name="login" action="login.php" method="post">' + t_login + '<input id="c_user" type="text" value="' + us + '" name="user" tabindex="1" accesskey="a"><input id="c_pass" type="password" value="" name="pass" tabindex="2"><input type="submit" value="ENTRAR" class="bot_login" tabindex="3"></form>';
            eventos();
            setTimeout("document.getElementById('c_pass').focus()", 50);
        }
    }
    c2.onblur = function() {
        if(c2.value=='') {
            us = document.getElementById('c_user').value;
            document.getElementById('login').innerHTML = '<form name="login" action="login.php" method="post">' + t_login + '<input id="c_user" type="text" value="' + us + '" name="user" tabindex="1" accesskey="a"><input id="c_pass" type="text" value="' + t_pass + '" name="pass" tabindex="2"><input type="submit" value="ENTRAR" class="bot_login" tabindex="3"></form>';
            eventos();
        }
    }
}
eventos();