> Assuming that in step 4 by "select" you meant double-click the word in red,
No, by 'select' I mean 'select'.
> I can't reproduce on Mac, neither using 3.6.12, nor using Firefox 4 nightlies.
That's the meaning of 'may', 'Reproducible: Sometimes' and comments on Launchpad. The occurrence seems to depend on the system used, on the page and on some circumstances. The choice of this particular example is because it always failed for me. But that's never for others. At least 7 people have confirmed to have seen something like this. But most people just shudder.
> This is the page that opens in a frame in the pop-up:
The error is not in that page. I said "Click on 'le TLF1' in that window" and the error is in a page like this
> It doesn't send the charset in HTTP headers at all and doesn't specify the
> charset in the HTML, as far as I can see.
Correct. No tlfi page does it. And that why I said about the second page that it "displays ISO8859-1 as UTF-8". That is the problem. It may probably affect only pages without character set definitions.
BTW, specifying the character set in HTTP is a crazy invention because it means that a program storing a page must modify it (and Firefox fails to do that).
> Can you reproduce using a clean profile?
Yes, it's now four years that I'm doing that on request. Somebody should conclude that the problem should be analyzed, not watched.
I said this. Isn't it what you mean?
> In VirtualBox[es], I have Ubuntu 10.04, 10.10, Windows 1.01, XP and 7 all [but 1.01 ;-)]
> exhibiting the Bug with native Firefox or its latest Ubuntu update.
> Maverick has 3.6.10 and my running Lucid [has] 3.6.11.
These systems were just installed or very little used (just for some installations and tests), Ubuntu ran the Firefox version that came with it and the latest Firefox was installed in Windows.
> With a build from mozilla.org?
This troubleshooting article is indecent. Asking naive people to erase all the cookies that were recorded to ease their life and then to make tests in a blank Firefox profile sounds like a bad joke.
In my running system I installed 3.6.12 and I checked that the problem still occurs in a blank profile.
> What's selected in View -> Character Encoding -> Autodetect?
That is a feature that is totally undocumented, that nobody understands [I have some good guesses], that everybody and his dog use to try to solve their problems the wrong way and that shouldn't exist.
Firefox is not supposed to autodetect anything and mu setting is most evidently (off).
Shall I say спасибо и пака?