Some editors don't work, except code editor

Taking a look to the source code it looks like it supports a graphic editor [js/gfx-editor.js](../tree/master/js/gfx-editor.js) for files with unknown extensions but it's not working for me.
Also I see that there is some kind of sound/music editor [tracker](../tree/master/tracker), but I don't know how to use it. I mean, how can users access to that feature from the home page?