Re: BUG: Colorize background of whitespace

[Oğuz]

On Thursday, October 26, 2023, Phi Debian <phi.debian@gmail.com> wrote:

> On Wed, Oct 25, 2023 at 5:01 PM Greg Wooledge <greg@wooledge.org> wrote:
>
> >
> > Ahh.  That wasn't clear to me.  Thanks.
> >
> >
> Ouch got caught the same way. This can be reduced to
>
> $ clear
> $ echo "\e[36;44;4m\nsome colored\ttext with\ttabs\e[m\n"
> $ <up><ret> # Recall and run prev command
> repeat the later until top lines scroll out.
>
> I added ;4 in the first \e i.e Underline to show that doing <tab> output is
> just a cursor movement (not a char painting) as would do any other cursor
> positioning esc seq.
>
> Doing so we see that on <tab> both the color and the underline are not
> decorated, on top lines, this is normal
>
> When the scroll out occurs, the underline is never painted, as expected,
> yet the BG color of the 'tab' is decorated.
>
> This is because there is a bogus \n right after the SGR sequence
> \e[36;44;4m\n this later \n say we open and SGR attribute, and \n will
> preserve it on scroll out, BUT colors at not completly SGR as stated here
>
> https://invisible-island.net/xterm/ctlseqs/ctlseqs.html search for
> *"ANSI X3.64-1979"*
>
>
> *When we remove the bogus \n all is normal*
>
> $ clear
> $ echo "\e[36;44;4m\some colored\ttext with\ttabs\e[m\n"
> <up><ret>
> many time.
>
>
> Generally speaking it is not good to leave an open SGR sequence before a
> \n, when emitting SGR before the \n it is wise to have a closing sequence
> \n[m\n
>

I can reproduce this behavior on all the terminals I have access to except
xterm on Solaris 10, it never paints the background of a tab, which is at
least consistent. I wonder what changed...


-- 
Oğuz