Rated 5 out of 5 stars

I have been hoping for improvements in TB's search function for quite a while. The is a significant improvement in search usability. THANK YOU!

A nice cosmetic improvement would be a searchbar that expands as you type, similar to the function of the Firefox extension "Searchbar Autosizer".

This review is for a previous version of the add-on (0.4.3). 

First, thanks for the feedback. The extension "Searchbar autosizer" seems good for Firefox but Thunderbird have a built-in autosizer behavior (different to that extension): when more icons are added to the toolbar, searchbox size decrease; when more space available, searchbox is bigger. I think this behavior is enough and works good, but if you know some cases in that this fail or is have problems please tell me!