No dedicated button but you assign one. On the far left there are four programable buttons. You can also assign functions to the FC7 footswitches too. The BK9 has a load of things that can be prorammed in. I've just started scratching the surface of adding these features to my Styles.
A useful on is being able to go from doing LH Bass to full arranger play with a button or one of the footswitches on the FC7. Never have to move your hands from the keyboard. Theres a long list of other useful functions. Check out the manuel online.