Firefox: Load context menu search tab in background

Problem

In recent versions of Firefox, if you select any text, right-click and choose Search Google (or any search engine), the new tab with these results is opened in the foreground.

Background

This default behaviour can be changed to load the tab in the background by setting browser.search.context.loadInBackground to true in about:config

Tried with: Firefox 13.0.1 on Windows 7 64-bit