Re: Start keybinding combination

[Eli Zaretskii]

> Date: Sun, 30 Jan 2022 20:15:39 +0100
> From: Ergus <spacibba@aol.com>
> 
> If a user wants to start a command like `C-x r b` I would like to change
> the mode-line color after the `C-x`. I suppose that this may be a call
> to a hook in the same place that updates the echo area inserting the
> current prefix.

What would such a hook do to produce the effect that you want?  The
mode-line color change will not be visible unless you force redisplay
of the mode line.