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

[IRIE Shinsuke]

> I think you misunderstood the doc string.  It means that instead of
> 
>   (window-line-height)
> 
> you should use
> 
>   (pos-visible-in-window-p)

`pos-visible-in-window-p' doesn't return a line height, so we can never
use it as a substitute of `window-line-height'.

> 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))

Why? If `window-line-height' returns nil, the result of this expression
becomes t or nil. What I want to obtain is a line height, not a boolean.

I guess the doc string means "`pos-visible-in-window-p' updates the
matrices' information, so call it before `window-line-height'."
In that case, however, it seems redisplaying is necessary for getting
the useful result. As I wrote in the previous mail, the following
expression properly returns the line height.

  (progn (redisplay t)
         (window-line-height))

I think `pos-visible-in-window-p' in the doc string should be changed
to `redisplay'.

IRIE Shinsuke