How to add menu button in Android bottom bar?
<p>In some apps like Skype, FireFox and Angry Birds there is a fourth menu button (which I have tried to draw) on the right which supplies app specific buttons. I want to know how can I add this button and then show some menu when this button is clicked.</p>

<p><img src="http://i.stack.imgur.com/L28qn.png" alt="enter image description here"></p>
