function EffectManager() {

    function construct() {

        this.setOpacity = function( el, opacity ) {

            opacity = ( opacity == 100 ) ? 99.999 : opacity;
            el.style.filter         = 'alpha(opacity:' + opacity + ')';
            el.style.KHTMLOpacity   = opacity/100;
            el.style.MozOpacity     = opacity/100;
            el.style.opacity        = opacity/100;
            el.emOpacity            = opacity;

        }; // end of 'setOpacity()'

        this.fadeIn = function( el, maxOpacity, callback ) {
        
            el.emOpacity = el.emOpacity || 0;
            el.emOpacity += 5;

            if ( el.emOpacity <= maxOpacity ) {
                Effect.setOpacity(el, el.emOpacity);
                el.emOpacity = el.emOpacity + 5;
                window.setTimeout(function() {
                    Effect.fadeIn(el, maxOpacity, callback);
                }, 10);
            }
            
            else {
                try { callback(); } catch(e) {};
            }

        }; // end of 'fadeIn()'

        this.fadeOut = function( el, minOpacity, callback ) {
        
            el.emOpacity = el.emOpacity || 100;
            el.emOpacity = el.emOpacity - 5;

            if ( el.emOpacity >= minOpacity ) {
                Effect.setOpacity(el, el.emOpacity);
                el.emOpacity -= 5;
                window.setTimeout(function() {
                    Effect.fadeOut(el, minOpacity, callback);
                }, 10);
            }
            
            else {
                try { callback(); } catch(e) {};
            }
        
        }; // end of 'fadeOut()'
        
    }

    return new construct();

};

var Effect = new EffectManager();