Stop looking for the Holy Grail of a usable restart button - they don't want you to have it !
BUT USE THIS INSTEAD : If you want a TRUE Firefox restart IN TWO CLICKS, do this:
1) Type about:restartrequired in your browser
2) Drag and drop that page to your toolbar
3) Click "Restart"
Done!
All credit to Andorio2007 - brilliant ! It works - no messing !