Fix invalid focus behavior when popup is shown

Author: lambdalisue

autoload/fern/internal/drawer/auto_restore_focus.vim

@@ -13,7 +13,7 @@ endfunction
 
 function! s:auto_restore_focus_pre() abort
   let s:info = {
-        \ 'nwin': winnr('$'),
+        \ 'nwin': s:nwin(),
         \ 'tabpage': tabpagenr(),
         \ 'prev': win_getid(winnr('#')),
         \}
@@ -24,12 +24,27 @@ function! s:auto_restore_focus() abort
   if s:info is# v:null
     return
   endif
-  if s:info.tabpage is# tabpagenr() && s:info.nwin > winnr('$')
+  if s:info.tabpage is# tabpagenr() && s:info.nwin > s:nwin()
     call win_gotoid(s:info.prev)
   endif
   let s:info = v:null
 endfunction
 
+if exists('*nvim_win_get_config')
+  " NOTE:
+  " Remove Neovim flating window from the total count
+  function! s:nwin() abort
+    return len(filter(
+          \ range(1, winnr('$')),
+          \ { _, v -> nvim_win_get_config(win_getid(v)).relative ==# '' },
+          \))
+  endfunction
+else
+  function! s:nwin() abort
+    return winnr('$')
+  endfunction
+endif
+
 augroup fern_internal_drawer_auto_restore_focus
   autocmd!
   autocmd WinEnter * nested call s:auto_restore_focus()