environment

nvim: v0.9.0-dev-198+g75ec1b720
mac: 12.6

minimal setting

" minimal setting
set runtimepath^=path/to/denops.vim
set runtimepath^=path/to/ddu.vim
set runtimepath^=path/to/ddu-kind-file
set runtimepath^=path/to/ddu-ui-filer
set runtimepath^=path/to/ddu-source-markdown

augroup Ddu
  autocmd!
  autocmd FileType ddu-filer nnoremap <buffer> o <Cmd>call ddu#ui#filer#do_action('expandItem', {'mode': 'toggle'})<CR>
augroup END

call ddu#custom#patch_global({
      \ 'sources': [{'name': 'markdown'}],
      \ 'ui': 'filer',
      \ 'uiParams': {'filer': {'sort': 'size'}}
      \ })

sample.md

# header1

hoge

## header2

fuga

### header3

hoge

# headerA

hgoe

## subHeaderA-1

hgoe

## subHeaderA-2

hgoe

### subSubHeaderA

hgoe

# headerB

hgoe

## subHeaderB

hgoe

instruction

1. open sample.md
2. call ddu#start()
   • The order of headers is not expected
     expected

     # header1
     ## header2
     ### header3
     # headerA
     ## subHeaderA-1
     ## subHeaderA-2
     ### subSubHeaderA
     # headerB
     ## subHeaderB
     

     actual

     # header1
     ## header2
     # headerA
     ## subHeaderA-2
     # headerB
     ### header3
     ## subHeaderA-1
     ### subSubHeaderA
     ## subHeaderB
     

3. move cursor at headerB
4. press o
5. press o
6. move cursor at subHeaderB
7. press o
8. move cursor at headerB
9. press o
   expected: expandItem
   actual: cursor down