Multifox Extension : Sign Into Multiple Same-Service Accounts

Multifox is an extension that allows Firefox to connect to websites using different user names.

Once you have installed the Multifox extension there are three ways to access it :
Menu : File > New Identity Profile
Tabs Context Menu : rightclick any tab > Open in a New Identity Profile
Context Menu for your bookmarks : Bookmarks > rightclick any bookmark > Open in a New Identity Profile

Any of the three will cause a new and separate window to open. Counting starts from 2 : notice a blue square with a number at the end of the Address Bar.
Logins made in windows with different numbers are isolated.
Clicking on any of the blue numbered squares will open a drop-down window with basic information about that particular identity profile.