And which normally is just some ten or twenty characters long, and
never gets wildly overallocated.

Nano would crash straight afterward if any of these asserts would fail,
so they don't add anything.  A few others are simply superfluous.

The functions read() and fwrite() take size_t, not ssize_t.

And line numbers in the file should be displayed as a long type instead
of an int, since the effective type of ssize_t is not int, but long.

This fixes https://savannah.gnu.org/bugs/?48622.

Achieve this by reusing the code that gives feedback when trying to
save a buffer while using --tempfile and the file has no name yet.

This fixes https://savannah.gnu.org/bugs/?48622.

Also improve or correct some comments.

If it would, the returned file descriptor would make nano crash,
because the corresponding stream has not been opened.  And when
returning zero instead (as the code did originally), nano would
open an empty buffer, although it claims to be reading the file.

In short: I think this is a leftover of an attempted fix of
https://savannah.gnu.org/bugs/?25297, from commit 2823c99e.

This fixes https://savannah.gnu.org/bugs/?49423.

Also remove some cluttering conditional compilation.

Instead of doing this in two places: after interpreting shortcuts,
and after injecting characters.

Mentioning "GNU nano" instead of "This program" and referring to the
website instead of to a postal address.

Add the keycodes and routines to allow the user to forego setting the
mark explicitly (with M-A / ^6) and instead quickly select a few words
or lines by holding down Shift together with the movement keys.

(Some combinations with Shift are swallowed by some terminal emulators.
To work around some of those, the combinations Shift+Alt+Left/Right work
as Shift+Home/End and Shift+Alt+Up/Down work as Shift+PageUp/PageDown.)

Instead be more specific and say that the directory is not writable.

This addresses https://bugs.debian.org/831636 reported by Christoph Biedl.

This fixes https://savannah.gnu.org/bugs/?47296.

Just like when reading a file fails.  It needs the user's attention.

Don't make it the responsibility of the executed functions to restore
the list of shortcuts of the edit window.  Just detect whether another
menu was displayed, and if so, redisplay the main menu.

Specifying an operating directory should either lead to a successfull
confinement, or nano should fail to start.

(Also: save the terminal settings as soon as possible, so that an early
die() will not restore uninitialized values.)

This fixes the first part of https://savannah.gnu.org/bugs/?47798 properly.

This fixes https://savannah.gnu.org/bugs/?48103.

(The fix is wasteful -- it should only discard the multidata if actually
the name *did* change, *and* if the applicable syntax changed.)

This fixes https://savannah.gnu.org/bugs/?48156.

Don't catch the NULL earlier, because we do want an error message when
opening the lockfile fails.

That is: don't mix the number of lines read with a warning about the
file being unwritable -- the former is just convenience information,
the latter is a must-see.

This fixes https://savannah.gnu.org/bugs/?48047.