Re: problem of display property [Re: list-charset-chars and unicode-bmp]

[Dave Love <d.love@dl.ac.uk>]

Kenichi Handa <handa@m17n.org> writes:

> That bug can be reproduced as below.
> 
> (insert "abc" (propertize "." 'display "<dot>") "def")
> 
> When you put cursor on `c' and type C-f, the cursor is
> placed on `d' instead of `<' of "<dot>", but C-x = shows
> that point is correctly on "."

That's actually not the only issue.  Another one in that context was
the behaviour if you put a display property on a newline to avoid the
table of characters being broken.

I haven't followed this, but I think that at least display properties
which are strings should work in pretty much the same way as
compositions, which seem to be better behaved, and images should
probably be likewise.  

Apart from issues of cursor movement, I think display text properties
should be uniquified on insertions the same way as compositions
currently are.  Thus if you cut and paste an image to duplicate it,
you should end up with two copies, not one.  This seems much more
likely to be what you want than merging the images due to text
properties of the adjacent text being the same.  (There's currently
code in image.el to do that sort of thing when you insert images
explicitly with the functions in image.el, but it's not a general
mechanism.)