Happens in 10.1.8.23rc1 & also 10.1.9.rc1.
I don't know how far it might go back?
(I can't believe no one has noticed this before?
Doesn't anyone use multiple windows?)
I'm pretty (?) sure earlier (no idea how early) versions of NoScript 10 did not cause this to happen.
verbatim copy from, https://forum.palemoon.org/viewtopic.php?f=63&t=19550
as the STR equally apply, except:
1) install NoScript 10
s/PM/FF/g(Windows) Taskbar Icons are Reordered when open from Session Restore
PM 28 (Win7 x64)
(I happen to be using the "portable" version, though I don't see where that should matter.)
New Profile
Set, Home Page to about:blank
Set, When PM Starts to -> Show windows & tabs from last time
Quit
Restart PM
Open 3 additional widows (so now a total of 4)
In each window do a search for the "number" of that window's relative position on the (Windows) taskbar
So window 1, do a search for '1', window 2, do a search for '2' ...
Taskbar icons show '1 at DuckDuckGo', '2 at DuckDuckGo' ...
Quit
Restart PM (should load from Session Restore)
Note the numbering of the windows.
Most likely there are not in 1,2,3,4 order.
1 will be 1.
Others are not deterministic.
Quit
Restart PM
Note the numbering of the windows.
Repeat...
In the case of PM 28, it does this "natively".
In the case of FF 10, NoScript causes it.
(An earlier "reorder" thread, https://forums.informaction.com/viewtop ... 10&t=23319 [& there have been others predating that]. From time to time this has cropped up, for various reasons, in various browsers, with various extensions - or none at all in PM 28.)