var game = new Phaser.Game(800, 600, Phaser.CANVAS, 'phaser-example', { preload: preload, create: create, render: render });

function preload() {
    game.load.spritesheet('button', 'assets/buttons/number-buttons.png', 160, 160);
}

var container;

function create() {

    container = game.add.group();

    // Add buttons to container.
    container.add(game.add.button(200, 100, 'button', bringMeToTop, this, 0, 0, 0));
    container.add(game.add.button(300, 100, 'button', bringMeToTop, this, 1, 1, 1));
    container.add(game.add.button(100, 200, 'button', bringMeToTop, this, 2, 2, 2));
    container.add(game.add.button(400, 200, 'button', bringMeToTop, this, 3, 3, 3));
    container.add(game.add.button(300, 300, 'button', bringMeToTop, this, 4, 4, 4));
    container.add(game.add.button(200, 300, 'button', bringMeToTop, this, 5, 5, 5));

}

function render() {

   game.debug.renderText('Tap or click button to bring it to the top.', 32, 32);

}

function bringMeToTop(btn) {

    container.bringToTop(btn);

}