Empty section titles do not 'cancel' sections

[josephwright]

As reported in https://tex.stackexchange.com/questions/422581/add-section-without-appearance-in-navigation-bar-with-beamer-v-3-50, using a deliberately-empty section heading does not 'cancel' the sectioning in

\documentclass{beamer}
\usetheme{Frankfurt}
\listfiles
\begin{document}
\begin{frame}
\tableofcontents
\end{frame}

\section{Sec1}
\begin{frame}
\frametitle{Frame1}
\end{frame}

\section{Sec2}
\begin{frame}
\frametitle{Frame2}
\end{frame}

\section{} % this works for v3.43, not for v3.50
\begin{frame}
\frametitle{Frame3}
\end{frame}

\end{document}

The change causing this to show is d0d1b4a855af8d6b960d75fe97d724cb4dfaae85, but I don't feel that's at fault really: it addresses a separate issue.

[ghost]

related problem: https://tex.stackexchange.com/questions/414525/beamer-singapore

https://tex.stackexchange.com/questions/423168/remove-slide-from-toc-and-navigation-in-beamer

[louisstuart96]

Seems like I've adjusted the behavior of \section in adding entry to nav file, in 7eb050b.

Edit: this is again related to changes for fixing #172. The logic of arranging this navigation style makes it impossible to handle all situations, especially those involving 'empty' sections and subsections.

[josephwright]

@louisstuart96 As I said, I think the old behaviour was an artefact of a bug, not by-design: it's not really predictable that an empty section name would have the effect it used to. We probably need an explicit command here to be 'outside of sections' (making sections into environments is too big a step).

[samcarter]

Note to self: Experiment with switching off miniframes selectively at https://github.com/samcarter/beamer/tree/nominiframe