Re: How to record the line number pixel width for each window.

[Eli Zaretskii <eliz@gnu.org>]

> Cc: "emacs-devel@gnu.org" <emacs-devel@gnu.org>
> From: Keith David Bershatsky <esq@lawlist.com>
> Date: Fri, 6 Dec 2019 09:07:10 -0800
> 
> Thank you, Eli, for reading and responding to this thread.  Once the redisplay cycle gets to the place where update_window is called, all simulations performed by moving IT have already concluded, and update_window is the launch-point for features 17684/22873.  I would be comfortable using an existing instance of screen simulation and perform the essence of line_number_display_width without launching a new session with start_display.  The goal is to be as efficient as possible when storing the values so that they are reliably accessible when update_window gets called.  My general feeling is that update_window is not the place to do screen simulations (moving IT) and running a _new_ instance of start_display for each window is not efficient.
> 
> Is there an existing instance of a running simulation for each window somewhere in xdisp.c where I could add the guts of line_number_display_width without launching a new start_display; and, if so, some pointers on where that might be located would be greatly appreciated?

I'm sorry, I don't understand the question.  What do you call
"simulation" in this context?