Today I discovered a Firefox feature that allows you to search within particular sites by prepending the search term with an @
:
This seems like an implementation of the similar Chrome behaviour, except that it only applies to the listed sites.
I also now realise that this feature is what was responsible for my occasionally landing on Amazon when I typed a search term too fast into the address bar. For this reason I find these shortcuts to be more trouble than they're worth, especially since there's already another implementation of the feature that allows you to specify any site to be searched.
However, I haven't been able to find any official documentation on this at all, let alone instructions for disabling the feature, and following the instructions here to disable the browser.newtabpage.activity-stream.improvesearch.topSiteSearchShortcuts
preference doesn't seem to make any difference, even after a restart.
How exactly do I disable this feature?