In the preceding commit, open_buffer() was changed so that it gets
told whether to load into a new buffer or not, so it is no longer
needed to convey this information through a flag.

And also prevent a theoretical crash for restricted prompt functions.

This fixes a regression introduced by commit 54103d8e: a crash that
can be triggered by running 'nano --restrict' and pressing <Insert>.

This addresses https://bugzilla.redhat.com/1558532.

When the file has just been read, it is in the state that it has
on disk, so there is nothing to undo.

This fixes https://savannah.gnu.org/bugs/?53387.

Signed-off-by: Liu Hao <lh_mouse@126.com>

When the cursor is on the first or last row of the edit window, and
thus Scroll-Down or Scroll-Up would push it offscreen, first move
the cursor away from the edge row and then scroll.

This fixes https://savannah.gnu.org/bugs/?53376.

This avoids a bunch of warnings when compiled with -pedantic:

	ISO C forbids comparison of ‘void *’ with function pointer

As, since commit 0e30177d, the scrollup and scrolldown commands
no longer intend to move the cursor, they should not be seen as
movement functions.

Also, it is not guaranteed that functions are ordered in the same
way in the binary as in the source code, so an ordered comparison
of function pointers will not always work.

This fixes https://savannah.gnu.org/bugs/?53333.

Reported-by: Brand Huntsman <alpha@qzx.com>

When just scrolling and the cursor does not need to change position
(that is: it is not on the first or last row of the edit window),
then edit_scroll() has handled everything and there is no need to
additionally redraw anything or update 'placewewant'.

Also, rename a parameter and invert its logic.

Instead of keeping the cursor in the same spot on the screen,
let the cursor move with the text (whenever possible).

This makes these functions behave the same as in Vim and Emacs.

Make them smaller to make them sound less like shouting.

This kind of addresses https://savannah.gnu.org/bugs/?53310.

This fixes https://savannah.gnu.org/bugs/?53317

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

This fixes https://savannah.gnu.org/bugs/?53269

.
Reported-by: Ashish Kunwar <dorkerdevil280@gmail.com>

The leak was mistakenly introduced by commit dc3618a1
-- probably as a leftover of testing things.

And adjust the comments accordingly.

Help texts are shown without any line numbers, so the full width
of the screen should be used to display the text.

This fixes https://savannah.gnu.org/bugs/?53308.

Signed-off-by: Brand Huntsman <alpha@qzx.com>

First the two that add something (ADD, ENTER), then the three that
delete something (BACK, DEL, JOIN), and then the one that changes
something (REPLACE).  Then the SPLITs, CUT, PASTE, and INSERT, and
then the INDENTs and COMMENTs, when they exist.

For cuts, pastes, and inserts, the lines have already been renumbered;
for indents, comments, and replacements, the line numbers cannot have
changed.  (And anyway, variable 'f' is not set for those cases.)

Only when lines get split (ENTER) or fused together (JOIN) do the later
lines need to be renumbered.  This mirrors what is done for do_redo().

The 'f' variable is used only in the ADD, BACK, DEL, ENTER, JOIN, and
REPLACE undo/redo cases.  So, avoid making a somewhat costly call when
it is entirely superfluous.  Rearrange the undo types to make checking
for the above six types easier.

This fixes https://savannah.gnu.org/bugs/?53272.