From the announcement:
Here are some of the key features updated with Classic 2.6:
We’ve upgraded the WYSIWYG and HTML editor tinyMCE. Not only does it have a cleaner look, but improved functionality.
Thanks to contributor luku, Browse Tags has additional functionality:
Default display of tags for both items and exhibits, with the ability to refine to just items or exhibits;
Tag sorts are now alphabetical, use count, and date created; and
You can search tags from within the browse tags page.
Read the full announcement here.