Firefox 52 Is The Last Version of Firefox For Windows XP and Vista (mspoweruser.com)
Mozilla has confirmed that Firefox 52, the new version of its browser it made available earlier this week, will be the last major version to support two legacy operating systems - Windows XP and Windows Vista. The company said future versions will require Windows users to be on a machine that has at a minimum Windows 7 running on it.
Not that I have any Vista machines any more, but why drop Vista support? What's available on 7 but not Vista, API-wise?
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
I think you are talking about the Pale Moon project. They claim to have no intention of dropping old-school NPAPI plugins and whatnot.