An annoying thing...

[mwenz]

Being a layout person, I wouldn't want to shift the burden of a breaking ellipsis onto a proofreader.

However, other than repurposing a hardback to a smaller paperback book, I have rarely been tasked with changing typefaces (which can cause the same type of breakage) or font size by the time I'm laying out a book or during the layout of the same. Pretty much size and leading is determined by the time I get the job. But it has happened, especially when laying out a book for lay people. Just not for actual publishing houses.

While print and the web have certain correlations, they are different--an exception would be when I've been tasked with converting a print publication to a reflowable eBook, which pretty much has direct correlation to the web.

But overall, I agree with Acorn. There are simple methods to ensure an ellipsis using periods and spaces do not break and if I was inclined to use that method, I would insert non-breaking thin spaces before/after and in between the periods. But what is more common for me is to alter the font's ellipsis to a wider proportion if/when needed. I make all my fonts to have a wider ellipsis characters (more space to each side and in between).

Compare most Apple supplied fonts (looking at you, San Francisco) versus say Times New Roman or even Arial. The ellipsis character in San Francisco is very compressed versus TNR/Arial.

[gwpriester]

Good points all.

If an extra dot got moved to the next line, it is easy enough to select the line and reduce the tracking until the rogue dot joins its mates. And the difference in most cases is not even noticeable.