I'm pretty new to GWD so there might be a more efficient way of doing this.
But I had to do something similar with a sound on/off button. All I did was create two buttons on top of each other (one with display:none; on it one without) and then attached 2 click events to each of the buttons (one to display:block; the other button, revealing it, and another to display:none; the current, to hide it).
You'll need a 3rd event on both buttons to play/pause.
Hope that helps!