Using the WebExtensions API I was unable to find anything about setting a preference in the about:config. In fact according to https://wiki.mozilla.org/WebExtensions/FAQ#Will_I_have_access_to_about:config_or_the_preferences.3F
I own the Pipelining Firefox extension, which I’m getting warnings about incompatibilities. However, it is kind of hard to update it when I can’t set about:config values. Any ideas?
Webextensions do not allow setting about:config preferences. It is something I do not think they will add.
Which preferences do you need access to?
network.http.pipelining
network.http.pipelining.aggressive
network.http.pipelining.ssl
network.http.proxy.pipelining
network.http.pipelining.max-optimistic-requests
nglayout.initialpaint.delay
Like Noit said, WebExtensions won’t implement direct access to preferences, but it’s possible to request APIs for specific features. In your case it would be some sort of HTTP Pipelining API. It seems unlikely that such a low-level API would be approved, since it’s known to cause some problems to users, but you can try and request it here.