Convenience method for setting the status text and icon to special values that are pre-configured to indicate
a "busy" state, usually for loading or processing activities.

@param {Object/String} config (optional) A config object in the same format supported by {@link #setStatus}, or a
string to use as the status text (in which case all other options for setStatus will be defaulted).  Use the
`text` and/or `iconCls` properties on the config to override the default {@link #busyText}
and {@link #busyIconCls} settings. If the config argument is not specified, {@link #busyText} and
{@link #busyIconCls} will be used in conjunction with all of the default options for {@link #setStatus}.
@return {Ext.ux.statusbar.StatusBar} this
function(o){
        if (Ext.isString(o)) {
            o = { text: o };
        }
        o = Ext.applyIf(o || {}, {
            text: this.busyText,
            iconCls: this.busyIconCls
        });
        return this.setStatus(o);
    }