Perhaps Ctrl+U?

Allow a user to change the default style of the message list scrollbar.
There is no easy way to set the default style for an object directly in
code, so I've updated every built-in theme to preserve the existing
style.

Signed-off-by: Konstantin Shelekhin <k.shelekhin@ftml.net>
---
 CHANGELOG.md             | 1 +
 config/style.go          | 4 ++++
 doc/aerc-stylesets.7.scd | 4 ++++
 stylesets/blue           | 1 +
 stylesets/default        | 1 +
 stylesets/dracula        | 1 +
 stylesets/nord           | 2 ++
[message trimmed]