Have you tried disabling that Ubuntu Modifications extension?

Beyond that, I don't currently run Ubuntu but I wonder if that issue is related to the Ubuntu build of Firefox? Maybe the Ubuntu fora - http://ubuntuforums.org/ - would be familiar with that 'defect'? Probably be a few hours before one of our Ubuntu users is around.

Thank you Edmeister,

The Ubuntu modification is just a start page with some links to Ubuntu sites, and launchers (Shortcuts in Windows) to report bugs and what not. Nothing that should reek havoc on a browser.

I have Googled the hell out of it: No Dice, and whenever I "Ask Ubuntu", I can't find the answers I am looking for, but strangely enough find answers to other stuff I searched high and low for, but completely out of context.

As for the menu bar: After opening and closing Firefox a few times, while researching other stuff (no changes made to Firefox or the PC), it magically reappeared out of nowhere!

Since I have had updates to Firefox almost biweekly, I can only assume that it is riddled with bugs, and I have already switched from Thunderbird to Evolution because it too went completely haywire out of the blue, for the umpteenth time, and I was sick and tired of having to fix it twice a month, spending countless hours messing with profiles and settings, reinstalling, and searching for solutions.

I do not ask directly for help, until I have exhausted all obvious and well documented avenues of troubleshooting and way beyond that. I can not understand how you could assumes that I would not have been able to trace down and spot a rogue plugin or addon, with the clear and detailed explanation of my efforts I gave in my original post.

These types of forums would be much more productive if there were a section in the profile where one would have to enter their level of intelligence, product knowledge and familiarity, computing skills... before they get to add all the cutesy stuff like avatars and emoticons. That way those offering help could get a better Idea of who they are dealing with and approach the subject with that in mind, and weather or not they can help in the first place.

Sorry that my level of expertise (or lack thereof) didn't meet your needs.

You don't have to apologize, I know this strange Firefox behavior will be incredibly difficult to pin point if at all. Necessity is the mother of invention, and my main teacher. I just hope that no one in authority marks this as solved, just because the menu came back. I may be back to report that it disappeared again.

Ubuntu 11.xx and later displays window menus in the control bar at the top of the screen with the switch to the Unity window manager.

Cor-el, The first line of my initial post is:

I am running Ubuntu Studio 15.10

Menus in the control bar are long gone (update your system). Besides I had a menu before it disappeared, hence I know where it was/is supposed to be.

READ FIRST, and only reply if you can be of actual help, or it happened to you to (for confirmation)!

I'm not using Ubuntu and have never such such Ubuntu Linux builds (OpenSUSE). I was repeating what I had read was happening in the past with Ubuntu versions, so thanks for posting that this no longer applies to current Ubuntu releases.

Are you using the Firefox version from the official Mozilla servers or the version from the repositories of your Linux distribution?

Try the version from the official Mozilla server if you currently use a version from the repositories of your Linux distribution.

Whenever one tries to install, or even considers installing anything not from the approved repositories in Ubuntu, all kinds of alarms sound and warning flags pop up, and I must assume there is a good reason for it.

As for now the menu has returned, and being new to Linux altogether, I have my hands full trying to get other stuff to work the way I need it to. So for now I am good, unless the problem comes back.

I have to be honest, I had little to no problems with Firefox up to about 2 years ago, until they started adding more and more UI elements taking up more and more space to do the exact same thing (with less choices) as a thin organized and fairly logical menu, only to end up hiding it all away again behind a single Icon, which essentially makes it a menu again. The improvements used to be under the hood, and it was way less buggy.

I firmly believe that if people do not take the time to read the choices, or can not grasp the logic, let alone get used to a well thought out system used universally on all platforms, in almost every application since the advent of the GUI: THE MENU "File" = do it to the whole file, "Edit" Edit the contents of a the file, and most of all "Help", then giving them a bunch of Icons, will just give them more to ignore, or get confused with, especially if it keeps changing.

If someone can't grasp simple concepts in the first place they are not equipped to handle such complex and flexible devices such as computers. I may sound harsh, but it's the reality. If people mistake a CD ROM tray for a retractable cup holder, The CD ROM does not need to be redesigned. You can't really reinvent the wheel, but it does have room for improvement.