Re: why does occur depropertize matching lines?

[Richard Stallman]

    Most faces don't change background color.  Only very special faces
    (that are very rarely used in buffers on which occur is usually
    called) have background different from default.

Yes, most such faces are used for temporary highlighting.

    > What we really want is to copy the face info from the source but "dim" it
    > a bit so it doesn't overshadow occur's own highlighting.

    There is one problem with dimmed faces: they might be not readable,
    especially for visually impaired users.

On some terminals, such dimming is not even possible, due to the limited
number of supported colors.

So I think you're right that we can simply change that face.
How about if you define a new face for the purpose, and set it
up in a way you think is good?  Please give pay attention to both
the light-background case and the dark-background case.