Maybe what you're looking for is not called the Taskbar in Firefox? What kinds of controls or functions are on the missing bar?

Along the bottom of my previous version of Firefox window, which was running on a different computer with Vista, was displayed the time which included a link to a calendar, and when a window was minimized if appeared as an icon at the bottom so when I clicked on it the window maximized, also a link to display the desktop and a link to display anti-malware program information, and various other icons.

Hmm, the Windows Taskbar should still be visible when Firefox is open, as long as Firefox is not in "full screen" view. You can tell Firefox is in full screen view if you can only see page content and no toolbars at the top. There are two kind of full screen:

• Browser full-screen: The F11 function key switches this on and off
• Media player or page full-screen: The Esc key cancels this

Is the Windows Taskbar visible when Firefox is minimized? If it's not visible, it might be set to "auto-hide". Move the mouse pointer all the way to the bottom of the screen to try to get the Taskbar to spring up into place. Then right-click it and choose Properties. Look for a checkbox for Auto-hide and turn that off. (Note: That's based on Windows 7, I don't have Windows 10 handy to confirm it works the same way.)

I've applied your tests for fullscreen and it's not in fullscreen. The taskbar won't spring into place - maybe it's not there at all. What I'll do is make do without the taskbar till I get a bit more used to Windows 10. It's possible that Windows 10 has moved the various components of the task bar onto the left hand margin where I can see the time is shown at bottom left, and if I put mouse pointer on Firefox icon it shows minimized windows. Thanks jscher2000 for spending the time to reply to my question :-)

Ha ha! Solved! I found this on the internet: "For years, the taskbar in Windows has always been positioned at the bottom of the screen. But, it doesn’t have to stay that way, you might prefer to have it at the top of the screen, or on the sides to maximize vertical screen real-estate. If you are new to the operating system, here’s how to change its position of the taskbar in Windows 10 (or any version of Windows for that matter):

   Step 1: Right-click the taskbar and click “Properties”
   Step 2: Under the “Taskbar” tab, find “Taskbar location on screen”
   Step 3: Change it to where you want the taskbar to be positioned"

I followed the instructions and the taskbar is now on the bottom. Source: onmsft dot com via Google. Some computer problems can require relentless searching for the solution regardless of how long it takes even though the answer is simple  :-)

An important point to make here is that it's Windows 10 that controls where the task bar goes on the screen and not Firefox, and also the task bar is part of Windows 10 and not part of the browser. For some reason I'd wrongly assumed that task bars come with browsers whereas they actually come with operating systems.