Thanks Kovid and BetterRed!
Kovid, thanks for setting me straight! I forget to mention that I am using Linux Mint 18.3. The version in the package manager was 2.55 -- slightly out of date!
I upgraded to 4.22 and the footnote issue is resolved -- as you said, I can now hit the escape key twice to get out of the footnotes.
Thank you for providing such a great program! I read epubs just about every day using your reader! I will be making another donation!
BetterRed -- I like the looks of your screen. I even started reading the text from the image you supplied. Will try to do the setup you describe -- very nice!
I'm happy now!
-Allen