Mozilla Firefox 41, the newest version of the world's most popular open source web browser, is out this week. It's meaner—if not leaner—than ever, with built-in instant messaging, user accounts featuring pictures and more. That leads me to wonder: Is Firefox becoming a full operating system unto itself?

Major new features in Firefox 41 include:

To be sure, this list of new features in Firefox 41 isn't tirelessly long. Still, Mozilla has been pushing out new versions of the browser about once a month. This represents more than a little new functionality to add in only several weeks' time.

The Firefox OS?

The fact that Firefox is growing up so quickly is striking. After all, it now comes with its very own instant messenger, of all things, not to mention something approaching a full-featured IDE for Web developers.

It seems like only yesterday (actually, it was about a decade ago, but I am losing track of time as I approach the age of 30) that Firefox was content to set itself apart from closed-source browsers, such as the venerable Microsoft (MSFT) Internet Explorer 6, by offering tabbed browsing. Watching the cool kids in my college dorm switch effortlessly between tabs is what made me a Firefox acolyte back in my youthful days.

Today, however, it almost seems as though Firefox wants to become an entire operating system. By the time Firefox 50 rolls around in less than a year's time, is it going to be doing its own networking, or mounting a special Firefox file system?

I hyperbolize, of course. I don't actually think Mozilla will go that far. But some of the features in recent releases extend well beyond the territory of a simple web browser.

Firefox isn't the first browser go down this path. Historically, Microsoft has included all manner of peculiar add-ons and application integration in Internet Explorer, mostly to help win the Browser Wars. (There's some irony in the fact that it was Microsoft's victory in that struggle that led to Firefox's birth.) And Opera—the hallowed, feature-rich browser that almost no one uses, but which has somehow managed to stick around for decades—has added features such as a BitTorrent client into its browser interface.

That's good for Opera and Internet Explorer. I don't use them, and I am not worried about how bloated they become with features that make my PC's application suite redundant.

I do use Firefox, however, and I would like it to remain just Firefox. If I want to send instant messages, I will download an app for that, such as Pidgin. If I want to upload more of my personal data, such as my browsing history, to third-party servers somewhere in the cloud, I'll spend more time using social media, not Firefox Accounts.

When I use the Firefox Web browser, I just want it to be a Web browser. Here's hoping it does that, and nothing more—because I'd be really sad if I had to experiment with Chrome again.