On the Mac, I edited /Applications/Firefox.app/Contents/MacOS/searchplugins/google.xml, changing http to https where appropriate. Now the builtin Google search

On the Mac, I edited /Applications/Firefox.app/Contents/MacOS/searchplugins/google.xml, changing http to https where appropriate. Now the builtin Google search plugin uses SSL system-wide (and so does the autocomplete, AKA suggest queries feature, if you edit that link, as well). Hopefully, Firefox will make this the default.