I've enabled true colors for Vim with success using:
set t_8f=\[[38;2;%lu;%lu;%lum
set t_8b=\[[48;2;%lu;%lu;%lum
set termguicolors
(check :h xterm-true-color
for more information)
I have then enabled a true color colorscheme to try the new setting, like:
set background=dark
colors deep-space
(https://github.com/tyrannicaltoucan/vim-deep-space)
Previously when using 256 colors I was able to get a transparent background by:
hi! Normal ctermbg=NONE guibg=NONE
hi! NonText ctermbg=NONE guibg=NONE
Now, this is not working anymore and I don't know any alternative. Is it possible to get transparent background with Vim under termguicolors
?
UPDATE
I've opened an issue on Vim's issue tracker: https://github.com/vim/vim/issues/981