Improve autocomplete results by excluding forums where the user lacks "view content" permission (aka they can see titles but not content).
Fix "Enable suggestions only for the first page of search results" was not applying for low search result count
Harden displaying "no results found" for search results (do not risk using cached search results).
This add-on is not vulnerable to leaking cached search results like Search Improvements v2.8.0/v2.8.1 did.
However if Search Improvements v2.8.0/v2.8.1 was installed then the site was still vulnerable to this issue
Improve detection of 'empty results' for various search result options (Search Improvements v2.8.0+ compatibility)
Add "Collapsible similar content" style property option (for this add-on's widget), allowing the similar thread box to be collapsed by the user and remembered via a cookie
Fix unexpected additional searches on no results for searches with no keywords could be triggered when "Enable suggestions only for the first page of search results" is enabled