This is a port of the phpBB version 3.0.x Mod Mark Edited Posts Unread that will set either the first (if it is the only post in the topic) or last post in a topic as unread if edited.
Download: https://github.com/RMcGirr83/phpbb-3.1- ... master.zip
- Copy the entire contents of the repository to
- Navigate in the ACP to Customise -> Extension Management -> Extensions.
- Click Enable.
This extension is not validated and should only be used on a test forum. If you install it on a live forum and issues arise don't blame me.