It would be horrible if the user expects to find numbered backups
of all the files that were changed but they are NOT there because
the config file contains a typo or the relevant directory was moved
or renamed or something.  So... if the specified backup directory
is not usable, nano should complain and simply not start up.

This fixes https://savannah.gnu.org/bugs/?51674

.
Reported-by: David Lawrence Ramsey <pooka109@gmail.com>

The new option 'set selectedcolor' applies to marked text, to the
currently selected file in the file browser, and to the highlighted
match during interactive search-and-replace.

Without them, nano still compiles for me, with everything enabled,
even when using --enable-debug, --enable-utf8, and --with-slang.

Commit 28beb3f9 added the 'forreal' parameter to prevent spotlight() from
placing the cursor wrongly due to an invalid placewewant.  However, since
the variable-width softwrap overhaul (specifically, since commit 8490f4ac),
place_the_cursor() no longer checks placewewant, so the parameter is no
longer needed.

Furthermore, dropping 'forreal' and thus always setting current_y won't
affect the operation of spotlight(), since the only functions that use
spotlight() (do_replace_loop() and do_int_spell_fix()) both call
edit_refresh() beforehand, which means that current_y will already
have been set to the value it will be set to again.

For some reason, when returning from suspension, SLang will produce
either a clipped error code (0xFF instead of 0xFFFF, when returning
from an externally induced suspension), or it will clip the code of
first subsequent keystroke to a single byte (when returning from a
normal, in-editor suspension: ^Z).

Side-step this by ignoring the clipped error code, and by using an
undefined control code as the first fake keystroke.  Ignoring the
clipped error code is not possible when using a single-byte locale,
otherwise the user would not be able to type the character with
code 0xFF (although it could still be entered with Esc Esc 255).

This fixes https://savannah.gnu.org/bugs/?51477.

Rename the corresponding rc-file option too, of course.

The help lines need to be redrawn one step after a justification
(whether it has been undone or not, to replace "Unjustify" with
"Uncut" again for ^U), and after switching buffers (to update a
possibly changed tag for ^T).

This fixes https://savannah.gnu.org/bugs/?51455.

In nano, -a is only effective when also -$ is given, so this will
not conflict with Pico since Pico does not know the -$ option.

Add the new function actual_last_column() to accomplish this.

get_chunk_row() replaces the formula "column / editwincols".

get_chunk_leftedge() replaces "(column / editwincols) * editwincols".

get_last_chunk_row() replaces "strlenpt() / editwincols".

get_last_chunk_leftedge() replaces "(strlenpt() / editwincols) * editwincols".

This prepares us for any changes in those formulas, and for more such
functions later.

(Well, redraw them when they're switched on, of course.)  Redraw
them so that they are shown correctly if their content changed.

This fixes https://savannah.gnu.org/bugs/?51356.
and fixes https://savannah.gnu.org/bugs/?51357.

The extra variable is not needed, because when having read from
standard input, the filename will simply be empty.  It will not
be empty for any other file that was read.

They can be given at the prompt, so it's better to accept them on the
command line too.

Also improve some comments.

And rename the function while there anyway.

A recent change (8dffb00f) removed this ability.  This change restores
it, and also allows reading from standard input multiple times -- maybe
not useful, but it works.

Also, conditionalize a statement that is only effective when
multiple file buffers are available.

Also, shorten two variable names.

This reduction is possible since the routine no longer loops when
it encounters a +NUMBER argument.

Also when a dash is the first "file" mentioned on the command line,
nano should show this buffer at startup and not the next.

This fixes https://savannah.gnu.org/bugs/?51207.

This fixes https://savannah.gnu.org/bugs/?51206.

Reading from standard input is a purely sequential affair --
no need to split it into two functions.

The old praxis of calling total_refresh() upon a SIGCONT was confusing,
because the screen would look as if nano had returned from suspension,
but in fact the shell was still active.

Instead of calling total_refresh(), put a no-op key into ncurses' buffer,
so that, when nano actually does return out of suspension (through 'fg'),
this key will be read and discarded, upon which nano will go sit and wait
for the next key, just before which it calls doupdate().  The latter is
all we need to get the entire screen restored.

This also fixes https://savannah.gnu.org/bugs/?51131 for "tiny".

When receiving a SIGCONT, don't call regenerate_screen() directly
but act as if a SIGWINCH occurred.  Also insert a dummy key, and
thus let the relevant input routine redraw the relevant subwindows.

Use KEY_F0 as the dummy key, as both Ncurses and Slang know it, and
it should normally do nothing at all.

This fixes https://savannah.gnu.org/bugs/?51124.

This has been done already during signal_init().

Apparently the curses on SunOS is less forgiving than the one on GNU.
Or rather: delwin(NULL) should just return an error, it shouldn't crash.

This fixes https://savannah.gnu.org/bugs/?51053

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Reported-by: John Wiersba <jrw32982@yahoo.com>
Solved-by: John Wiersba <jrw32982@yahoo.com>