hi Kevin, your Searchbar Autosizer add-on seems to be broken with multiprocess Firefox (e10s). If you have any questions about e10s support, just drop by the #e10s IRC channel on irc.mozilla.org. MDN also has a good introduction: https://developer.mozilla.org/en-US/Add-ons/Working_with_multiprocess_Firefox
The developer has been contacted through AMO.
I can't seem to replicate any e10s issue. I can't seem to resize the minimum in 42.0a2 at all though.