[Groff] Widow control: simple cases at least are working

[Larry Kollar]

I compiled last night's CVS with -DWIDOW_CONTROL and after studying the 
source (and making one patch to get  it to compile) it works with my 
test document. Here's a brief description of the commands enabled:

        .wdc [n]
                Set widow control. No argument, or a non-zero
                argument, enables widow control; zero disables it.
                No corresponding number register that I could find.

        .fpl
                Flush pending lines if widow control is enabled.
                (see below for usage)

Enabling widow control has a side effect that appears to disable the 
.ne request, allowing orphans to creep in. The .fpl request flushes 
pending lines, allowing .ne to do its job. In an -mm document, you 
could put the following at the beginning of your document (or in your 
locale file):

        .rn P P-orig
        .de P
        .  fpl
        .  P-orig
        .  ne 2
        ..
        .wdc

Note how the .fpl and .ne requests bracket the paragraph macro. This is 
the only ordering that achieves the desired results. The test file was 
an incomplete novel I've been working on; groff generated 47 pages of 
10-point type without a single widow or orphan (vs. several with widow 
control turned off). It didn't have any footers or footnotes, so I 
don't know whether that would interfere or not yet.

Definitely worth more testing....

--
Larry Kollar     k  o  l  l  a  r  @  a  l  l  t  e  l  .  n  e  t
Unix Text Processing: "UTP Revival"
http://home.alltel.net/kollar/utp/