Rated 4 out of 5 stars
This disables Context Search provided by https://addons.mozilla.org/en-US/firefox/addon/240 When I say disable, no search appears at all in a new tab. Nothing. However an easy fix for this is to make sure you have the Firefox Search showing in the Toolbar area (always removed it in the past but after reading all the reviews here for a fix I realised that was the problem -thanks to S3NTYN3L).
Also try the author's excellent Add To Search Bar https://addons.mozilla.org/en-US/firefox/addon/3682 (a REAL revolution to searching!).
Read ALL the reviews as you may find a fix that works for you.
It may be broke but it still gets 4 stars from me.