function setOpacity(eID, opacityLevel) {
    var eStyle = document.getElementById(eID).style;
    eStyle.opacity = opacityLevel / 100;
    eStyle.filter = 'alpha(opacity='+opacityLevel+')';
}


function fade(eID, startOpacity, stopOpacity, duration) {
    var speed = Math.round(duration / 100);
    var timer = 0;
    if (startOpacity < stopOpacity){ // fade in
        for (var i=startOpacity; i<=stopOpacity; i++) {
            setTimeout("setOpacity('"+eID+"',"+i+")", timer * speed);
            timer++;
        } return;
    }
    for (var i=startOpacity; i>=stopOpacity; i--) { // fade out
        setTimeout("setOpacity('"+eID+"',"+i+")", timer * speed);
        timer++;
    }
}

function getElm(eID) {
    return document.getElementById(eID);
}

function show(eID) {
    getElm(eID).style.display='block';
}

function hide(eID) {
    getElm(eID).style.display='none';
}

function fadeIn(eID) {
    setOpacity(eID, 0); show(eID); var timer = 0;
    for (var i=1; i<=100; i++) {
        setTimeout("setOpacity('"+eID+"',"+i+")", timer*2);
        timer++;
    }
}

function fadeOut(eID) {
    var timer = 2000;
    for (var i=100; i>=1; i--) {
        setTimeout("setOpacity('"+eID+"',"+i+")", timer*2);
        timer++;
    }
    setTimeout("hide('"+eID+"')", 105);
}
function hide_all(){
    hide('services_submenu');
    hide('faqs_submenu');
    hide('about_submenu');
    hide('samples_submenu');
}
function show_submenu(eID_show, eID_hide1, eID_hide2, eID_hide3) {
    fadeIn(eID_show);
    hide(eID_hide1);
    hide(eID_hide2);
    hide(eID_hide3);
}