Re: cursor doesn't show through transparent images in emacs 22, unlike emacs 21

[Richard Stallman <rms@gnu.org>]

    There is no sensible default.  What is useful as a mask depends on the
    image in question.  Using heuristic-mask can mean that the whole image
    flashes, but it can also mean that just a single corner pixel blinks.

1. So what?  Another default can't be worse than the present one,
   and it would be better MOST of the time.

2. Maybe we need another possible :mask value which would specify
   drawing the cursor in the way that you suggested.

3. If #2 is too complex to do now, maybe we should make it an error to
   fail to specify :mask on an image on a character in the buffer.
   That is simple.