Ok, i figured out that this was nearly the same issue as z-index.
I took a look at the .css and .html and found out that in the index.html this line:
is something like a fullscreen container that lay's his self over the screen.
So after commenting out the line, i can click the button. But the only thing hiding is the button itself, maybe thats just because i’m sitting on a laptop (not at home) and trying it throug my webbrowser. After refreshing it is hidden and blending back in when i click on the some space where the button was before. I’ll give it a try when i’m back home and hopefully it will work.
I’ll take a look to #debian to try to get help with the monitor freeze and post results here.