Highlight the first column when the records mode is on #5175
Description
The records mode gives a special meaning to the first column in the table, as it is used to determine record boundaries. The UI does not give any clue about this, apart from showing the record boundaries themselves, by changing the rows' background color.
Proposed solution
When in records mode, highlight the first column with a distinctive (but not disruptive) colour. I would add a shade to not just the column header, but also its contents.
Also, some small help button (such as a "?") could be added to the column header, with some help text explaining the role of this column.
Alternatives considered
Just like in #5173 the help button could be part of a tour, and not shown by default. Or it could be discarded voluntarily by the user.
Additional context
Suggested by a user during a feedback session.