I used to keep a big multi-colored category buttons there. To have a quick way for assigning general categories for thumbnail pictures.
Hi Kirk,
The one-click panel in version 3 was replaced by the much more versatile Favorites panel in version 5. With one click you can assign categories, copy files, send selected files to external programs, run scripts, and more.
Good question. Will add this to the IMatch 3 to IMatch 5 migration guide in the help.
If you just started using IMatch 5, check out the information here:
https://www.photools.com/community/index.php?board=17.0