Re: linum.el: problem (bug ?) fix and improvement

[Stefan Monnier]

>> What we'd like here is for the redisplay to ignore the margin property
>> placed on invisible text.
> Are you sure?  Only part of a line could be invisible, in which case
> it won't be easy to explain why we drop the before-string on the
> floor.  I would be uneasy to make such radical changes on behalf of a
> single use case.

Good point, but that's easy to fix: put the overlay over the whole line
of text rather than one the empty string at its beginning.

>> This boils down to making Emacs ignore
>> `before-string' properties placed at the beginning of invisible text.
>> I don't think it's always right to ignore them, tho.

> There's explicit code to do it the way we do now:

>         /* If there are before-strings at the start of invisible
>            text, and the text is invisible because of a text
>            property, arrange to show before-strings because 20.x did
>            it that way.  (If the text is invisible because of an
>            overlay property instead of a text property, this is
>            already handled in the overlay code.)  */
>         if (NILP (overlay)
>             && get_overlay_strings (it, it->stop_charpos))
>           {
>             handled = HANDLED_RECOMPUTE_PROPS;
it-> stack[it->sp - 1].display_ellipsis_p = display_ellipsis_p;
>           }

> Just undoing this would be regression from Emacs 20.x.

I know.  That's why I mention that maybe we should pay attention to the
stickiness so as to allow the Elisp code to choose which behavior
is desired.


        Stefan