How to make (force) line-break in Chapter Title (in ToC, Chapter, Header) – if possible?

I’ve found how to make different text for Title appearing in ToC, Chapter and headers Chapter title in header too long :

\chapter[medium-length title for TOC, if wanted]{full title name}
\chaptermark{short title for running headers}

How to make (“force”) line-break (if possible) in each of those three titles:

  • in ToC
  • in Chapter
  • in Header

?

Solutions Collecting From Web of "How to make (force) line-break in Chapter Title (in ToC, Chapter, Header) – if possible?"

The standard class page headers are really only set up for one line. If doing it a lot you should modify the page headers to set the mark text into a parbox, but for a one-off long entry you can put the parbox into the mark. So this breaks all three instances:

\chapter[medium-length\\ title for TOC, if wanted]{full\\ title name}
\chaptermark{\protect\parbox{.5\textwidth}{short title\\ for running headers}}