So I use Word for my SJG writing, and therefore for almost everything else I write.
One thing I like about my current version of Word is the navigation panel I can pop up on the left so I can navigate around using headings. However, if you use the SJG WYSIWYG, they aren't populated automatically into the Headings tab.
I'm not sure which GURPS author asked this question on Technet back in 2010, but when I looked tonight for how to auto-populate A-, B-, C-, and D-HEADs to the Headings list I found this:
Customized Headings in the Navigation Pane of Word 2010
That works in my current version of Word, too. Modify, click Format, click Paragraph, then change it from Body Text to level 1-4 (for A-D, respectively). It makes it very easy to navigate around my monster list (done in SJG WYSIWYG, because I often use them for books), Felltower (which has its own format), my GURPS book drafts, etc. Nice!
I hope that helps some other GURPS authors.