widget.js version 2.0.105 may be forcing some users to click twice to dismiss the overlay.
Created by: kmeddings
For example:
http://www.bmj.com/content/357/bmj.j1797 http://pubs.rsc.org/en/content/articlelanding/2017/cc/c6cc07684j
I don’t know if BMJ have implemented a non-standard method of loading the Crossref widget, but it looks like 2.0.105 binds the button events twice, which might explain the problem.
This code is from the very end of widget.js 2.0.105.
document.addEventListener("DOMContentLoaded", document.CROSSMARK.bind); document.CROSSMARK.bind();