Rikk & Rory.
Brilliant! Problem solved. And as a bonus, I was able to sidestep embarrassment & learn something as a result. I was not aware of the effects of the Shift+F keystrokes, so I learned something. Thus, I cannot be embarrassed about something that I never knew, right? (Of course, the fact that I must have inadvertently hit the Shift + F keys which caused my problem might be an indication of stupidity).
Now, as Terry can understand, I just have to remember the "Shift + F" sequence for future bouts of stupidity. :-)
Thanks, guys! Much appreciated!
Try cycling your [Shift][ F ] Key combination. It is a three position toggle that takes you through several pseudo full-screen modes. My guess is that you are stuck because of the mode you are in. One of the modes should restore your Apple Menu Bar to be always visible. Another mode will also restore the Lightroom Menu Bar to visible. This one should be draggable to the larger screen.