Vim local statusline doesn't set up correctly upon open new window

Question

I tried to write a small script to give the statusline distinguishable appearance on current and non-current window.

The local active and inactive statuslines are defined by the following code:

• Active statusline:

function! SttLine_Active(usesimple)
    setl statusline=
if (!a:usesimple)
    setl statusline+=\%#StatusBlockColour#
    setl statusline+=\ %{g:currentmode[mode()]}\ %0*

    setl statusline+=\%#StatusLineColour#
    setl statusline+=\ %p%%\(%L)\ ≡\ L%l\:%c\ \|%0*

    setl statusline+=\%#StatusFileColour#
    setl statusline+=\ [%{winnr()}]\ %f\ %m%=%0*

    setl statusline+=\%#StatusBlockColour#
    setl statusline+=\ ⌨\ %{&fileformat}:\ %y
    setl statusline+=\ %{&fileencoding?&fileencoding:&encoding}\ %0*
else
    setl statusline+=\%#StatusFileColour#
    setl statusline+=\ %f\ %m\ %=%0*
endif

endfunction

• Inactive statusline

function! SttLine_Inactive(usesimple)
    setl statusline=
if (!a:usesimple)
    setl statusline+=\%#StatusBlockGrey#
    setl statusline+=\ %{g:currentmode[mode()]}\ %0*

    setl statusline+=\%#StatusLineGrey#
    setl statusline+=\ %p%%\(%L)\ ≡\ L%l\:%c\ \|%0*

    setl statusline+=\%#StatusFileGrey#
    setl statusline+=\ [%{winnr()}]\ %f\ %m%=%0*

    setl statusline+=\%#StatusBlockGrey#
    setl statusline+=\ ⌨\ %{&fileformat}:\ %y
    setl statusline+=\ %{&fileencoding?&fileencoding:&encoding}\ %0*
else
    setl statusline+=\%#StatusFileGrey#
    setl statusline+=\ %f\ %m\ %=%0*
endif

endfunction

---

I then define some functions for different actions in vim, including VimEnter, WinNew, WinEnter and WinLeave as I want a different style for netrw window

• Function execute when vim start

function! SttLine_VimStart()
    let usesimple = (&filetype=="netrw") || (&filetype=="help")
    call SttLine_Active(usesimple)
endfunction

• Function that executes when a new window is opened:

function! SttLine_NewWin()
    let nWin  = bufnr("$")
let iwin     = 0
let hasnetrw = 0
while (iwin < nWin)
    if (getbufvar(iwin, "&filetype") == "netrw")
        let hasnetrw = 1
    endif

    let iwin += 1
endwhile

if (hasnetrw>0)
    vert res
    vert res -25
endif

endfunction

• Function executes on enter a window

function! SttLine_Enter()
    let usesimple = (&filetype=="netrw") || (&filetype=="help")
    call SttLine_Active(usesimple)
endfunction

• Function executes on leaving a window

function! SttLine_Leave()
    let usesimple = (&filetype=="netrw") || (&filetype=="help")
    call SttLine_Inactive(usesimple)
endfunction

---

Finally the augroup for those functions above

• augroup to call the correct statusline:

augroup Auto_Change_SttLine
    autocmd!
    autocmd VimEnter * call SttLine_VimStart()
    autocmd WinNew   * call SttLine_NewWin()
    autocmd WinEnter * call SttLine_Enter()
    autocmd WinLeave * call SttLine_Leave()
augroup END

---

• To test the script:

1. I open a file, let's call it file_01.txt from the terminal: $ vim file01.txt
2. then in vim, I open another file, file_02.txt: :new file_02.txt

• My problem

The first time, it worked as I expected. But for the next times I opened vim, it failed sometimes.

I realize that if I close file_02.txt before closing file_01.txt, the next time I start vim, my script fails.

In order to fix it, I need to close file_01.txt before closing file_02.txt.

• My question

What is causing this problem and how to make my script work regardless of the previous closing order?

Here is my youtube video demonstrating the steps I did to produce the error.

---

• Additional information

Below are the highlight I used for my statusline

hi StatusBlockColour    cterm=bold ctermfg=235 ctermbg=190
hi StatusBlockGrey      cterm=bold ctermfg=235 ctermbg=247
hi StatusLineColour     cterm=bold ctermfg=190 ctermbg=240
hi StatusLineGrey       cterm=bold ctermfg=245 ctermbg=240
hi StatusFileColour     cterm=bold ctermfg=208 ctermbg=240
hi StatusFileGrey       cterm=bold ctermfg=245 ctermbg=240

---

• Update 1 I just found some other issues in my .vimrc. I used

au BufWinLeave * mkview
au BufWinEnter * silent loadview

to restore the last view. It accidentally enabled me to run SttLine_Enter() and the result is bad.

Recently I added to my augroup a new au for BufWinEnter, so it became:

• (Updated) augroup to call the statusline:

augroup Auto_Change_SttLine
    autocmd!
    autocmd VimEnter    * call SttLine_VimStart()
    autocmd WinNew      * call SttLine_NewWin()
    autocmd BufWinEnter * call SttLine_Enter()
    autocmd WinEnter    * call SttLine_Enter()
    autocmd WinLeave    * call SttLine_Leave()
augroup END