Firefox autocomplete and dual monitors on OS X

There’s an irritating bug on Firefox for OSX when you’re using it with dual monitors. If you plugin the monitor after you’ve started Firefox, and it is in the secondary monitor, the autocomplete for URLs and for search queries will appear on the primary monitor. Very confusing. The solution is to restart Firefox (which retains the current set of opened websites in tabs and windows), for which I use the Restart Firefox plugin recommended by Sam Clark.