I’m hoping to address a few bugs in beamer over the next few days. One category that is always tricky is things linked to using \subsubsection. If you’ve read the beamer manual carefully, you’ll know that the original author of the class really didn’t want people to use \subsubsection in talks. However, he also didn’t ban it entirely, leaving me with a tricky situation. The problem is that while \subsubsection works, many of the things you might expect to happen from the relationship between \section and \subsection fail with \subsubsection, and from the code that may well be ‘by design’. Of course, I can change the ‘rules’, but beamer has been around a long time and it’s also somewhat complex code. As such, I’m always having to make judgements on how to deal with these bugs. My advice: don’t use \subsubection in beamer documents! Certainly don’t be surprised if when you ignore that advice odd things happen.