bug#63585: 29.0.91; (elisp) `Header Lines'

bug#63585: 29.0.91; (elisp) `Header Lines'

[Drew Adams]

This node describes header lines.  But it doesn't tell you, for example,
that a header line is not part of a buffer, which means you can't set
point there etc., which means you can't set point there to get info
about a face etc. there.

Info such as that is in node `Basic Windows'.  You can't understand
header lines without considering them in the context of windows.  Node
`Header Lines' should link to node `Basic Windows' (just as `Basic
Windows' already links to node `Header Lines').

A similar enhancement is likely relevant for other nodes, such as those
regarding mode lines.  `Basic Windows' links to `Mode Line Format', but
not the reverse.  And maybe `Mode Line Format' isn't the best mode-line
node to link to from `Basic Windows'?

A similar enhancement might be relevant for other things that are
called out in `Basic Windows': link from the nodes that describe them
to node `Basic Windows', to situate them in the context of a window.

In GNU Emacs 29.0.91 (build 2, x86_64-w64-mingw32)
 of 2023-05-14
Windowing system distributor `Microsoft Corp.', version 10.0.19045
Configured using:
 `configure --with-modules --without-dbus --with-native-compilation
 --without-compress-install --with-tree-sitter CFLAGS=-O2'