Re: Overlays disappearing during line-by-line scrolling

[Kim F. Storm]

Ralf Angeli <address@hidden> writes:

> Scrolling may
> look a bit strange because overlays with multi-line overlay strings
> are skipped as a whole and not displayed anymore.  So if you have
> something like this
>
>   first line first line [overlay overlay overlay overlay overlay
>   overlay overlay overlay overlay] second line second line
>
> and do `C-u 1 C-v' until the first line is scrolled out of the window,
> the first window line then will only contain
>
>   second line second line
>
> missing the start of the overlay on the second line of the example.

Yes, I noticed that myself, but didn't want to postpone the fixes any
further to look at this (minor) problem.

Actually, it seems quite difficult to get this right, as the redisplay
engine uses the field w.start_at_line_beg as an indication of whether
w.start is at the start of a line -- but the places that set and check
start_at_line_beg only look for a \n in the buffer, ignoring any
overlays that may make that newline character invisible on the display.

I'm sure it can be fixed -- I'm just not sure it is safe to do it
"this close" to the release...

-- 
Kim F. Storm <address@hidden> http://www.cua.dk