It is unclear if it's "required" to do this on RIS, but it's useful when
calling reset(1) after interactive programs have crashed and garbled up
the screen.
FWIW, other terminals do it as well (tested with XTerm, VTE, Kitty,
Alacritty, Linux VT).
Consider the following example:
printf '\e[?7l';\
for i in $(seq $(($(tput cols) - 1))); do printf a; done;\
printf '🙈\n';\
printf '\e[?7h'
Even though MODE_WRAP has been disabled, the emoji appeared on the next
line. This patch keeps wide glyphs on the same line and moves them to
the right-most possible position.
Fixes garbage selections when switching to/from the alternate screen.
How to reproduce:
- Be in primary screen.
- Select something.
- Run this (switches to alternate screen, positions the cursor at the
bottom, triggers selscroll(), and then goes back to primary screen):
tput smcup; tput cup $(tput lines) 0; echo foo; tput rmcup
- Notice how the (visual) selection now covers a different line.
The reason is that selscroll() calls selnormalize() and that cannot find
the original range anymore. It's all empty lines now, so it snaps to
"select the whole line".
dc.collen is the length of dc.col, not the maximum index, hence if x is
equal to dc.collen, then it's an error.
With config.def.h, the last valid index is 259, so this correctly
reports "black":
$ printf '\033]4;259;?\e\\'
260 is an invalid index and this reports garbage instead of printing an
error:
$ printf '\033]4;260;?\e\\'
Peter HofmannandHiltjo Posthuma