Adding ActionMenuView on Toolbar

ActionMenuView is a presentation of a series of menu options as a View. It provides several top level options as action buttons while spilling remaining options over as items in an overflow menu.

How to implement it on a Toolbar?

1. Add a Toolbar as app bar. See this.

2. Add each action button icon (drawable resource).

3. Create a menu resource file. Each menu item will be an action button. The tag app:showAsAction defines whether the action button will be showed if window have space to show it (app:showAsAction="ifRoom") or whether it only will be showed as an option on the overflow menu (app:showAsAction="never").

4. Inflate (Add) the menu to the toolbar. We inflate the menu on activity's method onCreateOptionsMenu. See the example below. 

override fun onCreateOptionsMenu(menu: Menu): Boolean {
    val inflater: MenuInflater = menuInflater
    inflater.inflate(R.menu.game_menu, menu)
    return true
}

5. Handle clicks on action button on activity's method onOptionsItemSelected. See the example below.

override fun onOptionsItemSelected(item: MenuItem): Boolean {
    // Handle item selection
    return when (item.itemId) {
        R.id.new_game -> {
            newGame()
            true
        }
        R.id.help -> {
            showHelp()
            true
        }
        else -> super.onOptionsItemSelected(item)
    }
}