bug#20847: [display engine] 25.0.50; company-mode popup makes point jump to an entirely different location

[Dmitry Gutov <dgutov@yandex.ru>]

On 06/21/2015 09:09 PM, Eli Zaretskii wrote:

> No, I expect the cursor to be drawn on the fringe, like the user
> expects.  (Or maybe I misunderstand what you meant by "earlier".)  You
> should give the 'cursor' property an integer value, so that it
> "covers" the buffer position of the newline.

Ok, thanks. I forgot that `cursor' can have an integer value.

> There are only 2 situations, from your POV: either a line goes all the
> way to the window edge, or it doesn't.

Could you suggest the best way to check whether the former is the case?

(>= (car (posn-col-row (posn-at-point)))
     (window-width))

 >   The former can happen either if there's a newline that ends a line, 
 > or if word-wrap is in effect.

Does that constitute at least three different cases we'd need to handle?

- Not near the window edge
- near the edge and newline
- near the edge and no newline?

> Yes, there could be such artifacts, but IMO losing some of the text is
> worse.

I'm not sure what you mean by "losing some of the text".

> And the problems you describe will be only on the lines
> actually used for the popup; the rest of the lines, which just copy
> buffer text into an overlay string, will look exactly like they did
> before, including the continuation markers.

Err, why this distinction?

If anything, I guess we could "replace" only the first newline inside 
the overlay display string with wrapping, while keeping the rest as 
newlines, because they are irrelevant to this bug.

>> Start the popup overlay at the end of the preceding line, and include a
>> newline in its display string (because there's no newline in the
>> buffer).
>
> I had no problems with that newline.

Sure. In those circumstances, moving point to the end of the overlay 
would be a no-op anyway.