Well, I finally decided to upgrade to FF 58... And give a shot to Kee. Even if I miss some of its excelent predecesor Keefox I must say that it worth to use (much better than KHPH). The explanatios of Luckykrat are very comprehensible explaining the limitations that are not on him but on Mozilla itself. The only thing is that I notice that Kee is also putting its icon into fields which are not for logins or pwd. For example in the AirOs page of my Nano5 I got the icon in the Mac address field and in the access point field where is not needed to be. I guess that Kee sees those field as login-pwd ones. Anyway I don't care for that (the icons are pretty, though :-). So 5 stars to Kee, and encouraging the Autor to keep improving it. (I have updated it to the newest version, but I don't see any visible changes yet).

1 Problem: If I check "...automatic login" in Options, when I close (log off) a page, as it returns to the login page, Kee keeps login again... I had to uncheck the (convenient BTW) option box and manually do login. What can it be done to fix this?
2 Problem fixed: I was seen in some secundary pages the Kee icon in some places it shouldn't be (I guess Kee was seen that as login/pwd) and even in a particular page the whole thing started to blink o tremble in a way I couldn't do nothing to stop it. I solved the problem opening and editing the connection login and in the last "Kee" tab, in URLs set as "Exact: The Url must match exactly including full path and query string" and then, in the additional frame I added the exact url of the main page (where the real login/pwd is). After doing this (and save the change!) I didn't see the icons in the secondary pages again.