Re: Emacs Lisp manual issues regarding overlays, display properties, margins, etc.

[Richard Stallman]

    > That seems like a bug to me.  It seems to me that a property that puts
    > something in the margin should not alter the appearance of the text
    > it is on.
    >
    > Does anyone think the current behavior is desirable?

    In any case, it follows the documentation

Two parts of the Lisp manual seem to conflict with each other.  It
would be straightforward to fix the one that doesn't agree with the
code.  I will do that.  But is there a good reason for the current
behavior?

    Maybe there should be a margin property (distinct from the current
    margin display spec) which specifies material to go in the margin
    (like the way the overlay before-string property works).

We don't want to make another property, because each kind of property
that display needs to check for slows it down.

But we could make another kind of margin display specification
that combines the effect of before-string and margin.
That would do what users would naturally expect.