function toggleOverview( override ) {

		if( typeof override === 'boolean' ) {
			override ? activateOverview() : deactivateOverview();
		}
		else {
			isOverview() ? deactivateOverview() : activateOverview();
		}

	}
Toggles the slide overview mode on and off.

@param {Boolean} override Optional flag which overrides the
toggle logic and forcibly sets the desired state. True means
overview is open, false means it's closed.