Sébastien Wilmet authored Dec 01, 2023 and Christian Hergert committed Dec 01, 2023

The bug was that the undo operation (Ctrl+z) moved the cursor to the
last line of the buffer.

When moving line(s) down or up (with Alt+Down or Alt+Up), there is the
special case of the buffer end that doesn't end with a newline
character.

The previous solution basically canonicalized the buffer by always
having a trailing newline. Then removing the trailing newline if it was
inserted.

So now, to fix the bug, a trailing newline is inserted *only* when the
end of the buffer is involved.

Basic regression/unit tests are included, so this bug should hopefully
not re-appear.