Re: Retrieving a webpages shows a blank screen when a 4xx HTTP status is returned. Not helpfull.

Dave,

> Greasemonkey has background scripts. Does it work in 52?

I'm not at all sure what you mean there.  It does allow me to set certain 
event listners, but those get set in GMs equivalent to "content_scripts". 
I've not seen anything mentioned about scripts that run at add-on start.

Than again, I've scraped my GM knowledge together from here-and-there, so 
its possible that I do not know everything.   If I want to create and add a 
GM background script, where should I look ?

Remark: I just did a quick google for "Greasemonkey 3.17 background scripts" 
and found nothing.

Regards,
Rudy Wieser