Re: Layered display API

[Eli Zaretskii <eliz@gnu.org>]

> From: Bo Lin <bo@dreamsphere.org>
> Cc: rudalics@gmx.at,  emacs-devel@gnu.org,  dgutov@yandex.ru
> Date: Thu, 14 Aug 2014 12:08:20 -0400
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> >> > What I meant is this: if you need to display below the last line of
> >> >> > the buffer text, put the overlay at EOB, and include newlines in the
> >> >> > overlay string when you need to move to the next screen line.  To
> >> >> > align text horizontally you could use spaces or align-to display
> >> >> > properties in the string.
> >> >> 
> >> >> Yes, I might try this, as soon as there's some suggestion how to handle 
> >> >> the problem of `line-prefix' in this multi-overlay approach.
> >> >
> >> > Find the longest prefix and align everything so that the left edge
> >> > keeps clear of that?
> >> 
> >> Zero length overlays don't get displayed so this won't work when the
> >> buffer is empty.
> >
> > When a buffer is empty, there are no line prefixes, right?  Or did I
> > misunderstand what you eman?
> 
> I thought this was about avoid padding the buffer text with
> newlines?

Sorry, it wasn't clear, as the previous citations talked about both.

So turning to the padding the buffer: it's not about padding with
newlines, it's about including newlines in overlay string.  After the
newline, the overlay string would have the text to be displayed beyond
the EOB.