请考虑以下示例：
\documentclass{beamer}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\showboxdepth=\maxdimen
\showboxbreadth=\maxdimen
\title{a}
\usetheme{Warsaw}
\begin{document}
\maketitle
\section{b}
\subsection{c}
\begin{frame}{d}
e
\end{frame}
\end{document}
Overfull \vbox (3.1309pt too high) has occurred while \output is active从幻灯片的样子来看，它传达的信息并不令人惊讶：
相关部分放大：
因此，出于某种原因，c（小节标题）的位置太高了。我不知道这么小的例子会出什么问题……
以下是日志文件的相关部分：
Overfull \vbox (3.1309pt too high) has occurred while \output is active
\vbox(11.3737+0.0)x182.09767
.\glue 0.0 plus 1.0fil
.\hbox(14.50461+0.0)x182.09767
..\vbox(14.50461+0.0)x182.09767
...\pdfcolorstack 0 push {1 g 1 G}
...\glue 1.50092
...\hbox(4.50278+2.00124)x182.09767
....\pdfstartlink(*+*)x* attr{/Border[0 0 0]/H/N/C[.5 .5 .5]} action goto name{Navigation2}
....\hbox(2.65184+0.0)x182.09767, glue set 161.89502fil
.....\glue 8.5359
.....\T1/cmss/m/n/6 c
.....\glue 0.0 plus 1.0fil
.....\glue 8.5359
....\pdfendlink
...\pdfcolorstack 0 pop
...\glue 1.50092
...\glue(\parskip) 0.0
...\glue(\baselineskip) 4.99876
...\hbox(0.0+0.0)x182.09767, glue set 91.04884fil
....\hbox(0.0+0.0)x0.0
....\penalty 10000
....\glue(\parfillskip) 0.0 plus 1.0fil
....\glue(\rightskip) 0.0 plus 1.0fil
.\glue 0.0 plus 1.0fil
我的投影机是 2017/08/22 v3.43（一切都是最新的，MikTeX 2.9）。
答案1
更新：这漏洞已修复
beamerv3.44，该示例现在可以正确运行。
负责生成标题的宏\insertsectionnavigation和的定义似乎存在小错误/不一致：\insertsubsectionnavigation
在中\insertsectionnavigation，我们有（beamerbasenavigation.sty，第 735-755 页）
\def\insertsectionnavigation#1{%
\hbox to #1{%
\vbox{{% [...]
% [...]
\dohead\vskip0.5625ex}}\hfil}}
而\insertsubsectionnavigation对于beamerbasenavigation.sty，第 769-792 页）
\def\insertsubsectionnavigation#1{%
\hbox to #1{%
\vbox{{%
% [...]
\dohead\vskip0.5625ex}\hfil}}}
请注意，在for\hfil之外，但在 for 之内。\vbox\insertsectionnavigation\insertsubsectionnavigation
如果你修复了的定义\insertsubsectionnavigation，警告就会消失，并且标题会正确显示：
\documentclass{beamer}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\showboxdepth=\maxdimen
\showboxbreadth=\maxdimen
\title{a}
\usetheme{Warsaw}
\makeatletter
\def\insertsubsectionnavigation#1{%
\hbox to #1{%
\vbox{{%
\usebeamerfont{subsection in head/foot}\usebeamercolor[fg]{subsection in head/foot}%
\vskip0.5625ex%
\beamer@currentsubsection=0%
\def\sectionentry##1##2##3##4##5{}%
\def\slideentry##1##2##3##4##5##6{\ifnum##6=\c@part\ifnum##1=\c@section%
\ifnum##2>\beamer@currentsubsection%
\beamer@currentsubsection=##2%
\def\insertsubsectionhead{##5}%
\def\insertsectionheadnumber{##1}%
\def\insertsubsectionheadnumber{##2}%
\def\insertpartheadnumber{##6}%
\setbox\beamer@tempbox=\hbox{\beamer@link(##4){%
\hbox to #1{\hskip0.3cm%
\ifnum\c@subsection=##2%
{\usebeamertemplate{subsection in head/foot}}%
\else%
{\usebeamertemplate{subsection in head/foot shaded}}%
\fi\hfil\hskip0.3cm}}}%
\ht\beamer@tempbox=1.6875ex\dp\beamer@tempbox=0.75ex%
\box\beamer@tempbox\fi\fi\fi}%
\dohead\vskip0.5625ex}}\hfil}} % FIXED
\makeatother
\begin{document}
\maketitle
\section{b}
\subsection{c}
\begin{frame}{d}
e
\end{frame}
