bug#42406: Mouse-wheel scrolling can be flickering

[Eli Zaretskii]

> From: Konrad Podczeck <konrad.podczeck@univie.ac.at>
> Date: Mon, 14 Dec 2020 21:48:36 +0100
> Cc: Alan Third <alan@idiocy.org>,
>  42406@debbugs.gnu.org
> 
> > As explained in my other message, avoiding to call
> > wset_update_mode_line will cause subtle redisplay bugs.
>  
> Which bug could I encounter, for example?

Mode lines of non-selected windows could fail to update when they
should (e.g., if the buffer displayed in a non-selected window
changes), tool-bar buttons that change their appearance depending on
the Emacs state (e.g., the "Copy" button becomes sensitive only when
there's region) could fail to react to state changes, menu-bar items
that depend on modes and global state could fail to update.  That sort
of bugs.