Causes FF12 and 13 spell check to not work properly Rated 1 out of 5 stars
You know that menu that appears when you right click on a blank text field? Since FF12, I've had a problem with that menu also appearing when I right click on a word that Firefox shows as misspelled instead of a list of suggestions.
Restarting in safe mode determined that it was an add-on. A process of disabling add-ons one by one determined that the problem was caused by Multi-Links. That add-on has also had a long history of causing the wrong menu to appear when I right click an image followed immediately by another menu appearing when I left click to get rid of the erroneous menu. So I finally decided to just remove it and learn to do without it.