Column context menu
Right-clicking Column label opens this context menu.
Rename column or track…
Renames this column of the associated track.
If the track associated with this column is not associated with any other column, the track will be renamed. In all other cases, the column itself.
Duplicate column
Creates a copy of this column and its associated track and inserts it to the right.
Insert column left
Inserts a new empty column to the left and associates it with a newly created REAPER track.
Insert column right
Inserts a new empty column to the right and associates it with a newly created REAPER track.