I just downloaded ArcGIS 10.6.1 and the main menu in Arc Catalog stand-alone (not window) is detached from the interface and it won't dock. This is annoying as it gets in the way of standard menu items and top files in the list. How do I get it docked? Thanks for the information.
If you reset your application profile, it should return it to the default template and move all of the toolbars back to the default position: Resetting your ArcGIS application profile Try renaming the folder at this location: C:\Users\username\AppData\Roaming\Esri\Desktop10.6\ArcCatalog to ArcCatalog_OLD (please don't delete this folder).