This is a simple tutorial how to add a support for easier filtering of threads by their thread prefix. After this change prefixes will be changed to URL links. When you click to them, threads with the selected prefix will be displayed.

1) In ACP open and edit "forumdisplay_thread" template and find this line of code:

{$thread['threadprefix']}

replace it by this line of code:

<a href="{$mybb->settings['bburl']}/forumdisplay.php?fid={$mybb->input['fid']}&prefix={$thread['prefix']}" style="text-decoration: none !important;">{$thread['threadprefix']}</a>

2) Save and reload (Ctrl+F5) your page to see the result!

3) Click on any thread prefix and check the output 

Thanks for this great little hack, much easier than using the dropdown to select a prefix!  The filtering appears to be limited to the forum the threads are currently being viewed from.  It would be wonderful if this could extend beyond the threads within that forum but I guess that's more of a search instead of a filter.  This could allow prefix links work from places like the homepage or portal.