We apologize for the instability of composr.app and appreciate your patience. We are working on the statistics addon and trying to find an optimal way to store and render data. Unfortunately, we have yet to find a solution that can handle the traffic (and therefore, tens of millions of statistical records) of composr.app. We're working hard on one.
HTML5 now allows native context menu manipulation:
https://www.w3.org/blog/2016/11/html-5-1-is-the-gold-standard/?pk_campaign=feed&pk_kwd=html-5-1-is-the-gold-standard
Some time until adopted http://caniuse.com/#feat=menu
EDIT: Chrome removed support, because there's a lack of interest and people don't like the spec (should be JS based, not HTML based).
https://www.w3.org/blog/2016/11/html-5-1-is-the-gold-standard/?pk_campaign=feed&pk_kwd=html-5-1-is-the-gold-standard
Some time until adopted http://caniuse.com/#feat=menu
EDIT: Chrome removed support, because there's a lack of interest and people don't like the spec (should be JS based, not HTML based).