Re: Fwd: overlay face property not used for after-string property

[Joe Wells <jbw@macs.hw.ac.uk>]

Richard Stallman <rms@gnu.org> writes:

>     I don't think I can fix it, but I remember discussion of something similar
>     a few years ago where the conclusion was thatit was better to not apply a
>     property of the overlay (e.g. `face' although I believe the discussion was
>     about `invisible') to the (after|before)-string because it's easier to add
>     this property manually to the relevant string than to "undo" the effect of
>     the overlay's property from the string.
>
> That sounds like a valid argument -- but it applies equally to the
> before-string and the after-string.  It can't be right to apply the
> property to one and not the other.
>
> Can someone write a patch so that the overlay's face property (and
> other display-related properties) won't apply to its before-string?
>
> Joe, what do you think about that as a solution?

I think that would be an improvement.  I think the best solution would
be for the face property of an overlay (and similar properties) to not
apply to the before-string, the after-string, _and_ the display
property of the overlay.

Note that there are additional problems.  One example (which I have
already reported) is that the face of the character in the buffer
after the overlay start location (which is not even in the overlay if
the overlay is of length zero) is applied to the before-string and
display properties of the overlay.  Another example (which I think I
have not previously reported) is that the face of the character in the
buffer _after_ the overlay end location (which is _never_ in the
overlay) is applied to the after-string property.

Also, fixing this issue this way leaves behind the difficulty of
adding a face property manually to a property string (before-string,
after-string, or display) which already has face properties.

-- 
Joe