bug#39902: 28.0.50; Marking in dired with active region

[Drew Adams]

> (1) Docstring of `dired-mark' says
>   "If the region is active, mark all files in the region."
> 
> However, the file in the last line of the region is never marked, even
> if the region spans the whole line of this file.

The problem seems to be that movement doesn't
put the cursor where you (and `dired-mark')
expect - the full lines are not selected.

If you do, say, `C-SPC', then `p p p', `then C-a',
then `m' (`dired-mark') then the full 3 lines are
selected and they get marked.  Similarly, if you
select the lines with the mouse.

Should `dired-mark' mark all lines that have any
of their chars selected, instead of lines that
have _all_ of their chars selected?  Maybe so.