环境中的边注放置错误（换行）

Question

在环境中（参见environ），我将一个marginnote放在环境标题旁边。标题包含一些文本。如果该文本延伸到行尾（但甚至比 MWE 显示的要早一点），则边注不再放在环境标题旁边（似乎在 中发生了换行marginnote）。为什么？我该如何修复环境以避免这种情况？我猜环境标题会生成一个额外的空格（在哪里？），然后将边注推到下一行。

\documentclass{scrbook}
\usepackage[american]{babel}
\usepackage{amsmath}
\usepackage{marginnote}
\usepackage{hyperref}

% Environment
\newcounter{counter}% environment counter
\numberwithin{counter}{chapter}% number counter within chapters
\makeatletter
\newenvironment{environ}[2][]{\refstepcounter{counter}\par
  \normalfont\topsep6\p@\@plus6\p@\relax
  \trivlist
\item[\hskip\labelsep\sffamily\bfseries MyEnviro~\thecounter\ #1]%
  \marginnote{OtherEnviro p.~\pageref{#2}}\ignorespaces
}{%
  \endtrivlist\@endpefalse
}
\makeatother

\begin{document}
\chapter{That's the problem}

\begin{environ}[(Some text which covers the amount of space to show the problem)]{foobar}\\
  This seems odd (vertical space, wrong placement 'OtherEnviro') because the line
  is actually not ending there.
\end{environ}

\begin{environ}[(Some shorter text to show that there's no problem here)]{foobar}\\
  This is okay
\end{environ}
\end{document}

Answer 1

\marginnote添加一个不可见的框，类似于。在添加之后的\mbox{}分隔符 ( \labelsep)和空行中的结果。顺便说一句：如果没有这个框，则会导致\item\mbox{}\\LaTeX Error: There's no line here to end.

因此，为了避免该问题，请将其设置\labelsep为 0pt 并（可选）将其添加\\到环境定义中。

\documentclass{scrbook}
\usepackage[american]{babel}
\usepackage{amsmath}
\usepackage{marginnote}
\usepackage{hyperref}

% Environment
\newcounter{counter}% environment counter
\numberwithin{counter}{chapter}% number counter within chapters
\makeatletter
\newenvironment{environ}[2][]{\refstepcounter{counter}\par
  \normalfont\topsep6\p@\@plus6\p@\relax
  \trivlist
  \labelsep 0pt
\item[\hskip\labelsep\sffamily\bfseries MyEnviro~\thecounter\ #1]%
  \marginnote{OtherEnviro p.~\pageref{#2}}\\*
  \ignorespaces
}{%
  \endtrivlist\@endpefalse
}
\makeatother

\begin{document}
\chapter{That's the problem}

\begin{environ}[(Some text which covers the amount of space to show the problem)]{foobar}
  This seems odd (vertical space, wrong placement 'OtherEnviro') because the line
  is actually not ending there.
\end{environ}

\begin{environ}[(Some shorter text to show that there's no problem here)]{foobar}
  This is okay
\end{environ}
\end{document}

我使用过\\*，以\\避免在标题。