Firefox location bar loses focus with HTTPS Everywhere and suggestions enabled
While typing in the location bar with suggestions enabled (browser.urlbar.autocomplete.enabled set to true), after the first characters typed have caused some suggestions to appear, as soon as a character is typed that does not match any of the suggestions, the location bar loses focus. This problem disappears when HTTPS Everywhere is disabled and reappears when HTTPS Everywhere is enabled. (It also disappears when browser.urlbar.autocomplete.enabled is set to false, but that reduces usability of Firefox too much to be a workaround.)
The bug does not occur with every instance of Firefox, and if an instance of Firefox does not exhibit the problem, it will not exhibit it even if running for a long time. On the other hand, if an instance of Firefox has the problem, it will not disappear while that instance is running. It seems to me that the probability of getting a buggy instance of Firefox is correlated to the amount of history data available, i.e. probability is somewhat low with a fresh install of Firefox, then gradually rises as the history database fills up.
I am using Firefox 16.0.1 (and have had the problem for several releases of Firefox before that) with NoScript and AdBlock Plus installed as extensions. There are no plugins. OS is GNU/Linux using Debian 6.0.6 as base distribution.