Hi there,
I am using the native notifications inPhoneGap with Ext.device.Notification.
As the native code is broken at several points I wrote an override for this.
Here is the solution:

Code:
Ext.define('App.override.device.notification.PhoneGap', {
    override: 'Ext.device.notification.PhoneGap',


    show: function () {
        var config = this.callParent(arguments),
            buttons = (config.buttons),
            onShowCallback = function (index) {
                if (config.callback) {
                    config.callback.apply(config.scope, (config.buttons) ? [config.buttons[index - 1].itemId.toLowerCase()] : []);
                }
            };
        var ln = buttons.length;
        if (ln && typeof buttons[0] != "string") {
            var newButtons = [], i;
            for (i = 0; i < ln; i++) {newButtons.push(buttons[i].text);}
            buttons = newButtons.join(',');
        }
        navigator.notification.confirm(config.message, onShowCallback, config.title, buttons);
    }
});
I hope you find this helpful.