Unable to use mouse after startup

[htfy96]

ArchLinux with Gnome3.20.3

➜  ~ nvim -v    
NVIM v0.1.5-611-gdcbd1c7
Build type: Dev
Compilation: /usr/bin/cc -march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -g -fvar-tracking-assignments -Wconversion -Og -g -Wall -Wextra -pedantic -Wno-unused-parameter -Wstrict-prototypes -std=gnu99 -Wvla -fstack-protector-strong -fdiagnostics-color=auto -DINCLUDE_GENERATED_DECLARATIONS -DHAVE_CONFIG_H -D_GNU_SOURCE -I/tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/build/config -I/tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/src -I/usr/include -I/usr/include -I/usr/include -I/usr/include -I/usr/include -I/usr/include -I/usr/include -I/tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/build/src/nvim/auto -I/tmp/yaourt-tmp-lz/aur-neovim-git/src/neovim-git/build/include
编译者 lz@lzPC

Optional features included (+) or not (-): +acl   +iconv    +jemalloc +tui      
For differences from Vim, see :help vim-differences

➜  ~  ~/.local/bin/pynvim  --prog 'nvim --embed -u NONE /home/lz/code/test.cpp'

All mouse-related functions such as scrolling, clicking don't work. However after I press : and then <esc>, this problem will certainly disappear.