@Schorry92 EDIT: please see etienne’s fix below
[spoiler]It appears that this is broken now, I’ve made a pen as an example though: http://codepen.io/billythekid/pen/JbMeNd?editors=0010
Adding buttons or removing buttons seems to no longer work. Perhaps there’s been a version update since I last used this about a year ago? It may be that if you use a previous version it’ll work or someone else here may be better placed to advise. Sorry I can’t be of more help.[/spoiler]