Yes, FF operates differently when you use a different operating system.
Just like the earlier poster who said he had a MAC (where we assume he meant an APPLE computer), your environments are different, ergo you get different results.
Let me ask you this, when you downloaded Firefox, did you download the version for Windows or the one for Linux ?
Of course the windows version.
It’s simply a port to that platform. Do you understand what progammers mean when they say “port” to a platform ?
You can download the source code for the Windows version and the source code for the Linux version and compare them.
I downloaded the Linux source; it’s tons of C++; I highly doubt, from just a quick glance, that it makes use of much besides display primitives, network and file i/o, user interaction, other OS primitives like threads, etc.
The latest “esr” (extended support) release is here:
ftp://ftp.mozilla.org/pub/mozilla.org/firefox/releases/24.5.0esr/
You will notice a directory for each platform:
linux686 (32bit)
linux86_64 (64bit)
mac
win32
and you’ll notice a directory
source
under which there is a unified source archive; there’s just one set of programs. This leads me to guess that they’ve used the standard approach of not relying too heavily on platform specifics of any one platform that are high-level and would entail a lot of work to recreate on the other platforms.
IMHO, again, I haven’t looked at it, but if you’d like to prove that they “use” Internet Explorer, you certainly could look in the source code and find where they do.