Unity 5 GUI system

Using the new GUI interface, I have a Button at the edge of my screen. When clicked, I want it to animate towards the middle of the screen to reveal a sidebar.

So I set the Transition on the Button to ‘Animation’ and click ‘Auto Generate Animation’. In the Animation window I do the necessary animations I need within the ‘Pressed’ section.

When I test it, the button will animate out and reveal the sidebar, but as soon as I release the button, it snaps back to the original position.

I know this is because it is the ‘Pressed’ state, but there is no option for a ‘Clicked’ state.

Does anyone know how to press a button, have it play an animation and stop there without it snapping back?

Ive had a look at the video found here: http://unity3d.com/learn/tutorials/modules/beginner/ui/ui-button which was helpful to start me off but theres not much more documentation that I could find on Button functionality for the new GUI.

Maybe use toggle since what you want is a button that has both off and clicked (on) states