Re: [Nano-devel] fixing the tickle (was: Smooth Horizontal Scroll patch)

[Benno Schulenberg]

Hi Mark,

On Mon, May 19, 2014, at 17:59, Mark Majeres wrote:
> I think that problem may have been there to begin with.  It just
> became more noticeable with the patch.

Indeed, it was.  But the beginning was just five days ago,
by a patch by myself.  :|

> I tracked it down to the following lines in edit_draw()

Yeah, minutes after sending the mail, I realized that my patch might
be the culprit: it pokes into the last column.  But when I worked on
that "patch", I found that poking the terminal before displaying the
line didn't work, it had to be after.  But it seems that, when I changed
the poke to a non-breaking space, I never tried poking it *before* the
first painting of the line.  I tried it now, and it works.  Good.

I've pushed that single change into SVN, to fix this bug before the
release of 2.3.3.  (Chris?  I think it's ready now.)

>     if (using_utf8())
>       /* Tickle the terminal into displaying two-column characters
>        * properly, using Unicode 00A0 (No-Break Space). */
>       mvwaddstr(edit, line, COLS - 1, "\xC2\xA0\x00");
> 
> I have no idea what these are doing, some sort of escape code sent to
> the terminal I guess.

It was just some invisible character to get the terminal to display
multi-column characters at the start of the line properly -- it is a
"fix" for https://savannah.gnu.org/bugs/?31743 .  Try its test file
(https://savannah.gnu.org/support/download.php?file_id=29242),
make the lines just one position shorter than the width of your
terminal, and see how the second long line gets misdisplayed when
you do <End> <Home> on that line (when you comment out the
tickle from edit_draw()).

> I just rearranged editdraw() slightly so the last column is always
> drawn after the escape codes are sent.  Seems to work now.

As said above, I've pushed that change into SVN, and attributed it
to you.  The rest of the patch will come later, after 2.3.3.

Regards,

Benno

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