I noticed this Q at SO and, as it turns out, the Questioner found the solution himself and added the answer in the comments below it. Great! Another useful question answered. But it leaves behind a question that can be closed, simply because it's self-answered. So, how about adding another "Close" option to questions that have been answered in the original question or as part of a comment by the questioner himself? Otherways, this question will remain open until Saint Juttemus day, as we say here in the Netherlands. :-)
Trying to get every question into an "answered" or "closed" state isn't productive on a site like SO. You'd just never be able to do it and waste tons of effort trying. Some people attach an (unnecessary) stigma with closing, and "answered" questions still aren't finished/complete/closed — "closed" is simply used differently here than elsewhere.
In this case, I would (and did) post a comment that the OP should answer their own question. This behavior is even encouraged with a badge.
Argueing with @Gnome:
They are likely to ignore such encouraging comments. Once they solved their problem they don't care about the site. And they don't care about guys like me who sometimes look for unanswered questions under a given tag. I search for
The fact, that you never be able to get rid of all false unanswered questions, doesn't mean that we shouldn't do it at all. At least tidying a not so popular tag from false questions is feasible.
So this is from a point of view of a guy who seeks difficult questions willing to answer them. Aren't such guys productive for SO? Don't they deserve a little support?
Note also that self-answering is sometimes downvoted (Should I not answer my own questions?), so a question asker caring about his reputation may not do that.