When I include a URL — or another long continuous chunks of text — in a footnote in Microsoft Word, the preceding line often ends up having lots of white space. The usual fix for that is to include an optional hyphen, but I don't want the URL to be hyphenated; I want it to break at a slash or a dot. At times, I've entered manual line breaks, but that's not optimal, because I don't want it to break at a fixed place; I want it to break at the place that yields the least internal white space, and that might change as the earlier lines in the footnote change, or as the article gets reformatted.
I've just stumbled on what seems like a good solution: Insert / Symbol / Special Characters / No-Width Optional Break. You can insert this special character wherever you're willing to see the long continuous chunk be broken; it's still not automatic, but it's better than the alternatives I've noticed (at least the alternatives that let me stick with Word). And if you find yourself doing this often, you can easily assign a shortcut key to this special symbol.
Oddly, Word's Help feature doesn't seem to discuss this; I had tried earlier to search for optional line break, but couldn't find anything useful. So I thought I'd pass this along for the benefit of others who might be facing the same problem I had faced in the past.
UPDATE: Commenter Tim_K points out the downside: "The solution works in terms of improving the appearance of the Word document, but when I tried it, add the special character made it so the URL no longer acted as a link to take you to the website in question. I guess you can get around this by copying and pasting the URL into you web browser, but it's far from an ideal solution. What's wanted is to improve the appearance of the Word document and have the URL function as a link." I don't find this to be much of a problem since most of my links aren't likely to be the sort of things that the typical reader will want to follow. But it may well be a downside for others; and it sure would be great if Microsoft kept this from happening, as they could easily do.
FURTHER UPDATE: Commenter Steven Joyce suggests a fix to Tim_K's problem: "Highlight the full URL (both halves), right-click and select 'Edit Hyperlink' or 'Hyperlink', and then put the correct URL (without the special character) in the 'Address' box."