bug#19300: 24.4.51; visual-line-mode messes up after-string rendering when it spans all window columns

[Dmitry Gutov <dgutov@yandex.ru>]

On 12/08/2014 06:04 PM, Eli Zaretskii wrote:

> visual-line-mode doesn't care about newlines, when the stuff before
> the newline overflows the window width.

Right. That's why I made sure the stuff before and after each newline 
fits the window.

>> and the length of each line there equals to the value reported by
>> (window-width).
>
> Not here:

I'm sure it does. It depends on the test data only: 34 columns in the 
first example, 32 columns in the second.

> I need to resize a bit the windows showing the overlays, in
> order to see something similar to your images.

The scenarios intentionally resize the newly popped window to make sure 
it's the right size.

>> Without overlays, even when visual-line-mode is enabled, I can make a
>> window body 34 chars wide and type 34 characters (maybe including
>> spaces) on a line without seeing them break up.
>
> Are you saying that if you insert your test-string-1 and test-string-2
> into the respective windows as buffer text, you see them displayed
> differently than the overlay in the same window?

Hmm, actually no. Sorry about that. So the examples could be simplified 
to just insert the respective test string, without overlays.

But I can open a different window, enable visual-line-mode, take its 
(window-width), insert that numbers of characters on one line and not 
see them wrapped.

Could this be a bug in `enlarge-window-horizontally' and/or `window-width'?

> If so, I cannot
> reproduce this: I see both the overlay and the buffer text wrap
> exactly identically.

Have you installed Fira Mono and set it up, like the first code line in 
the example does? This doesn't happen with the default Ubuntu font in 
the Emacs master, although in emacs-24 it did when I tried.