[throwaway2048]

the chrome UI is vastly more restrictive than the Firefox one (addons effectively can not modify it in any way), so i'm not sure what you are saying here.

[Jabbermonkey]

Looks like the current target for feature parity with FF56 may be around 2020 or later, based on projected fixes of critical bugs.

Toolbar:

https://bugzilla.mozilla.org/show_bug.cgi?id=1215064

Session managers:

https://bugzilla.mozilla.org/show_bug.cgi?id=1427928 https://bugzilla.mozilla.org/show_bug.cgi?id=1474130

It shouldn't take three plus years to fix an upgrade. The goal was good, WebExtensions are a significant step forward as a concept. Planning, execution and post-transition management sucked.