A never ending discussion in the Mozilla Community is the shortcut (yes or no) to the profile manager (see picture) of Mozilla products like Firefox or Thunderbird.
Known from the very first version (1.0) of both applications, this special shortcut in the meantime is banned by drivers like Mike Connor or Benjamin Smedberg, see bug#263840 or bug#322823.
Since this time supporters of Mozilla community must help desperate users with broken profiles in support forums, and a lot of wiki's are filled with instructions to find the profile manager or make a shortcut to launch other/new profiles, like here or here or here.
None other than Spread Firefox co-founder Asa Dotzler now wrote the 1001th make-a-profile-manager-shortcut-instruction to launch a specific firefox profile on Mac.
I do not understand this anymore: drivers, give us back the Profile-manager-shortcut by default installation, and let community stop to write complex instructions.
use Kaosmos extension Profile Switcher, which adds a submenu to "File"-menu in Firefox/Thunderbird.