blend shows emojis behind window or popup

[adelarsq]

• nvim --version:

NVIM v0.5.0-416-g2b00d1d09
Build type: Release
LuaJIT 2.1.0-beta3
Compilation: /Applications/Xcode-10.1.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=1 -O2 -DNDEBUG -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wshadow -Wconversion -Wmissing-prototypes -Wimplicit-fallthrough -Wvla -fstack-protector-strong -fno-common -fdiagnostics-color=auto -DINCLUDE_GENERATED_DECLARATIONS -D_GNU_SOURCE -DNVIM_MSGPACK_HAS_FLOAT32 -DNVIM_UNIBI_HAS_VAR_FROM -DMIN_LOG_LEVEL=3 -I/Users/travis/build/neovim/bot-ci/build/neovim/build/config -I/Users/travis/build/neovim/bot-ci/build/neovim/src -I/Users/travis/build/neovim/bot-ci/build/neovim/.deps/usr/include -I/usr/include -I/usr/local/opt/gettext/include -I/Users/travis/build/neovim/bot-ci/build/neovim/build/src/nvim/auto -I/Users/travis/build/neovim/bot-ci/build/neovim/build/include
Compilado por travis@Traviss-Mac-6.local

Features: +acl +iconv +tui
See ":help feature-compile"

    arquivo vimrc de sistema: "$VIM/sysinit.vim"
            padrão para $VIM: "/share/nvim"

Run :checkhealth for more info

• vim -u DEFAULTS (version: ) behaves differently? No
• Operating system/version: Mac OS X
• Terminal name/version: iTerm 3.3.9
• $TERM: xterm-256color

Steps to reproduce using nvim -u NORC

• Enable transparency:

set pumblend=9
set winblend=9

• Open any buffer with emoji text
• Use autocomplete or any other window/popup with transparency.

Actual behaviour

Actually the emojis are showed as if it belonged to the window/popup with transparency:

Expected behaviour

For a better user experience would be nice if the char is a emoji it to be hided in the blended window/popup. Something like:

[bfredl]

Tricky. I suppose most terminal take no account at all of foreground color for emoji? We could add a flag, or do this automatically when blend<50 and 'emoji' is set (in the compositor layer, so multigrid UI:s still can do proper blending).

[tssm]

I think replacing the emoji with a whitespace would do the job