I decided to stop developling MyBB addons. You can find details here: lukasamd/MyBB-View_Unread_posts#25

This plugin checks to see if there are already similar threads when we write new topic (using AJAX). If yes, we can simply check them.

Admin can configure:

• Additional (X)HTML code before related threads list (in global template)
• Fulltext / LIKE search mode
• Minimum length of phrase
• Open links on new / the same window or tab
• Excluded forums
• Excluded words
• Search on the same forum
• Max search threads age
• Display forum info
• Delay from press last key to search
• Change all plugin templates

INFO: This plugin add link to author website (only for web spiders). If you do not want this, do not use plugin, or make donate and contact author.