    /**
     * Private utility class that manages the internal Shadow cache.
     * @private
     */
    Ext.define('Ext.ShadowPool', {
        singleton: true,
        requires: ['Ext.DomHelper'],

        markup: (function() {
            return Ext.String.format(
                '<div class="{0}{1}-shadow" role="presentation"></div>',
                Ext.baseCSSPrefix,
                Ext.isIE && !Ext.supports.CSS3BoxShadow ? 'ie' : 'css'
            );
        }()),

        shadows: [],

        pull: function() {
            var sh = this.shadows.shift();
            if (!sh) {
                sh = Ext.get(Ext.DomHelper.insertHtml("beforeBegin", document.body.firstChild, this.markup));
                sh.autoBoxAdjust = false;
            }
            return sh;
        },

        push: function(sh) {
            this.shadows.push(sh);
        },

        reset: function() {
            var shadows = [].concat(this.shadows),
                s,
                sLen    = shadows.length;

            for (s = 0; s < sLen; s++) {
                shadows[s].remove();
            }

            this.shadows = [];
        }
    });