Sorry - just very tired of people tossing out ESR as a solution to this problem. It isn’t - at best, it just kicks the can down the road. At worst, it’s continuing to support a company that’s shown utter disregard for a huge portion of its user base by the way they’ve handled XUL deprecation. No one’s saying XUL didn’t need to go - it did. What’s frustrating is the complete removal of it without before providing a viable replacement and the accompanying big shrug / middle finger to anyone who relies on XUL-based extensions and can’t switch to the neutered WE version (see Tile Tabs and Tree Style Tab).
As a long-time Firefox user, I’m extremely disappointed by the way Mozilla has handled this. I’ll use 57 for dev tools and bookmark sync, but Waterfox or Vivaldi will be my daily driver.
The problem is that certain valuable extensions are impossible to update, because the new plugin API doesn't expose the necessary functionality. E.g. Keysnail, which will break because Mozilla won't expose the ability to override C-n.
Mozilla should have taken the time to release a fully-baked extension API before deleting the old API; then it really would have been on the extension authors. Between this and the utter destruction of Sync's security guarantees a few years back, the Cliqz keylogger fiasco & the Pocket fiasco, as well as the WebRTC fiasco (as well as the defenstration of Brendan Eich), I'm very disappointed in Mozilla these days.
This has been pointed out to Mozilla multiple times.
See https://wiki.mozilla.org/Add-ons/Firefox57#Compat._Table
16 legacy, 4 ready for 57. a few of them i use very often: automatic save folder, save file to, video downloadhelper, downthemall!, search by image for google, image zoom, copy links