The following allows for the hideLoading() method of Chart to work correctly. There was no definition for opacity modifications in the animate: and the Highcharts passes a function in options.complete to remove the loading layer from display.

Code:
    animate: function (el, params, options){
        if (params.width!==undefined) {
            Ext.get(el).setWidth(parseInt(params.width), true);
        }
        else if (params.height!==undefined) {
            Ext.get(el).setHeight(parseInt(params.height), true);
        }
        else if (params.left!==undefined) {
            Ext.get(el).setLeft(parseInt(params.left));
        }
        else if (params.opacity!==undefined) {
            Ext.get(el).setOpacity(parseInt(params.opacity),true);
            if (options.complete !== undefined && typeof options.complete == 'function'){
                options.complete();
            }
        } else {
            Ext.get(el).setTop(parseInt(params.top));
        }
    },