lib/Ext/Container.js
function(activeItem, animation) {
        var layout = this.getLayout(),
            defaultAnimation;

        if (this.activeItemAnimation) {
            this.activeItemAnimation.destroy();
        }
        this.activeItemAnimation = animation = new Ext.fx.layout.Card(animation);
        if (animation && layout.isCard) {
            animation.setLayout(layout);
            defaultAnimation = layout.getAnimation();
            if (defaultAnimation) {
                defaultAnimation.disable();
            }
            animation.on('animationend', function() {
                if (defaultAnimation) {
                    defaultAnimation.enable();
                }
                animation.destroy();
            }, this);
        }
        return this.setActiveItem(activeItem);
    }
function(activeItem, animation) {
        var layout = this.getLayout(),
            defaultAnimation;

        if (this.activeItemAnimation) {
            this.activeItemAnimation.destroy();
        }
        this.activeItemAnimation = animation = new Ext.fx.layout.Card(animation);
        if (animation && layout.isCard) {
            animation.setLayout(layout);
            defaultAnimation = layout.getAnimation();
            if (defaultAnimation) {
                defaultAnimation.disable();
            }
            animation.on('animationend', function() {
                if (defaultAnimation) {
                    defaultAnimation.enable();
                }
                animation.destroy();
            }, this);
        }
        return this.setActiveItem(activeItem);
    }
Animates to the supplied `activeItem` with a specified animation. Currently this only works
with a Card layout.  This passed animation will override any default animations on the
container, for a single card switch. The animation will be destroyed when complete.
@param {Object/Number} activeItem The item or item index to make active.
@param {Object/Ext.fx.layout.Card} animation Card animation configuration or instance.