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

[Richard Stallman]

    An additional point.  Suppose the overlay has both before-string and
    display properties.  (Yes, you need to do this if you want to use an
    overlay to replace the text in the buffer and display multiple images
    or a mixture of text and images.)  The display property replaces the
    display of the text in the buffer (and possibly specifies a different
    face for it).  It makes no logical sense in this case for the display
    of the before-string to use the face of a character in the buffer that
    is being concealed.

In some cases it does.  Consider a paragraph that is italicized
with a text property.  Shouldn't substitute text be italic by default?