[Users] deeply indented threads

[Paul]

On Tue, 31 Oct 2017 12:14:35 +0000
Dave Howorth <dave at howorth.org.uk> wrote: 

> For most of my folders, I use threaded display. In some - I'm
> thinking of one particular mailing list at the moment - threads
> sometimes get quite deep, with the result that the Subject moves
> ever rightwards and disappears entirely.

Quite a belated answer, not sure what reminded me of your question...
Anyway, there is a hidden pref 'enable_hscrollbar' which adds a
horizontal scrollbar to the message list. It's on by default, I guess
you turned it off at some point.

with regards

Paul