how to display tabline in Oni?

[haifengkao]

Oni Version: 0.3.9
Neovim Version (Linux only): NVIM v0.2.1-1-g1b0d573
Operating System: OSX 10.14.5

Issue:
how to display tabline in Oni?

Expected behavior:
should have buffer line on the top

Actual behavior:
Oni only has tabs on the top
the buffer line is not displayed

Steps to reproduce:
install https://github.com/vim-airline/vim-airline
add let g:airline#extensions#tabline#enabled = 1 in init.vim

[oni-bot]

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