Undercurl Rendering Errors #847
Description
Mintty seems to mishandle rewriting a line with undercurl (curly underline). It draws extra lines where they do not belong, and fails to clear them until they are explicitly overridden. They disappear when the window is moved or resized.
Reproducing
The issue occurs sporadically on the command line, but I found it could be reproduced more consistently in Vim.
- Run the following file in Vim with
vim --clean -u mintty-bug.vim mintty-bug.vim - Scroll up and down the file, and move the cursor around the Lorem Ipsum text
Just to prove that Vim is working correctly, you can change the first two lines to:
let &t_Cs="\<Esc>[31m"
let &t_Ce="\<Esc>[0m"
Vim is emitting the control sequences at the correct locations.
mintty-bug.vim
let &t_Cs="\<Esc>[4:3m"
let &t_Ce="\<Esc>[4:0m"
set colorcolumn=60
hi SpellBad ctermbg=NONE cterm=undercurl
set spell
" Lorem ipsum dolor sit amet, consectetur
" adipiscing elit. Nunc ante augue, lacinia at mi
" id, commodo luctus turpis. Donec ut bibendum
" ipsum. Aenean sagittis sed enim sed cursus.
" Fusce interdum purus nec arcu fermentum, id
" imperdiet arcu tincidunt. Phasellus id nibh
" varius, rhoncus risus eu, sollicitudin augue.
" Aliquam vehicula non ante a placerat. Morbi
" vehicula venenatis lorem, non pharetra urna
" vehicula nec. Nunc vehicula condimentum lectus
" et facilisis. Pellentesque volutpat neque
" lectus, finibus consectetur neque accumsan eu.
" Duis sodales et velit vitae accumsan. Sed
" lobortis imperdiet nunc vel ullamcorper. Aliquam
" id erat diam. Nullam sed ipsum nec felis
" venenatis dapibus. Integer faucibus est
" faucibus, dapibus neque in, tempor arcu.
" Maecenas vestibulum nibh et congue condimentum.
"
" Duis consectetur ultricies erat eu placerat.
" Praesent felis libero, rutrum in bibendum sit
" amet, dignissim eget neque. Phasellus luctus
" erat eu convallis mattis. Nunc quis libero
" libero. Nam libero velit, tristique fringilla
" ornare vitae, fringilla bibendum felis. Aenean
" vulputate, nunc in laoreet viverra, nibh sem
" aliquet mauris, quis euismod mi sapien eu
" turpis. Maecenas sit amet condimentum leo.
" Maecenas in nulla et ex tempus feugiat. Nulla
" facilisi.