You might have to search for an exact add on to do this, or there might be a password manager extension that you can find, but I could find this:

• Idle Login Add on

Other addons can be found at addons.mozilla.org.

Thankyou guigs2 for taking the time to reply. I actually had already checked addons for a few weeks if you must be reassured. I do not understand why it was assumed otherwise. The add-on you linked does not do as requested. Password Managers do not automate login as a single sign-on does. Password Managers still require the user to to go to each page. It can prefill and then login. A single sign-on is a common application feature that signs on completely a list of applications e.g. the user does not need to navigate to each of the applications.

Thankyou for your time.