I should have looked at that more carefully before posting. This and some other things didn’t work after upgrading to the most recent trunk version. I hadn’t changed the “Default location balloon format” code. It had worked before upgrading, so I assumed the problem was due to a bug in the new version. However, I just noticed that the following portion isn’t valid:
<a href="#_LOCATIONPAGEURL</a">
I changed it to this and the link works fine:
</a><a href="#_LOCATIONPAGEURL">Details</a>
Could something have changed that in the database when the version was activated?
EDIT: I was typing this while you were posting your message above and hadn’t read what you wrote.