Subject: Re: bug#6763: 24.0.50.1; Doc string of `window-line-height'

From: Eli Zaretskii <[email-masked]>
Date: Fri, 30 Jul 2010 17:53:07 +0300

> Date: Fri, 30 Jul 2010 22:55:17 +0900
> From: IRIE Shinsuke <[email-masked]>
> Cc: 
> 
> Doc string of `window-line-height' says:
> 
>   Return nil if window display is not up-to-date.  In that case, use
>   `pos-visible-in-window-p' to obtain the information.
> 
> However, using `pos-visible-in-window-p' seems ineffectual.
> In fact, the following expression often returns nil:
> 
>   (progn (pos-visible-in-window-p)
>          (window-line-height))

I think you misunderstood the doc string.  It means that instead of

  (window-line-height)

you should use

  (pos-visible-in-window-p)

Using progn doesn't cut it, since it always returns the value of the
last form.  What you mean is probably this:

  (or (window-line-height)
      (pos-visible-in-window-p))

If this doesn't work for you, please show a precise recipe, starting
from "emacs -Q", to reproduce the situation where
pos-visible-in-window-p returns nil when it shouldn't.