[mini.files] Highlight target window

[pkazmier]

Update: see #2177 (comment) for the correct implementation.

Have you ever forgotten which window you were in when you opened 'mini.files' and been unsure where your selected file will appear? If so, you might like this auto command. When there’s at least one split on-screen, it highlights the target window while you’re in the 'mini.files' explorer.

  -- Returns the number of splits (non-floating windows) on screen
  local count_splits = function()
    return vim
      .iter(vim.api.nvim_tabpage_list_wins(0))
      :filter(function(w) return vim.api.nvim_win_get_config(w).relative == "" end)
      :fold(-1, function(acc, _) return acc + 1 end)
  end

  -- Sets an option and returns a function to restore the original value
  local set_option = function(name, value, opts)
    local original = vim.api.nvim_get_option_value(name, opts)
    vim.api.nvim_set_option_value(name, value, opts)
    return function() vim.api.nvim_set_option_value(name, original, opts) end
  end

  vim.api.nvim_create_autocmd("User", {
    desc = "Highlight target window while 'mini.files' is open",
    pattern = "MiniFilesExplorerOpen",
    callback = function()
      -- Only highlight a window if there is more than one possible target
      if count_splits() == 0 then return end
      local target = MiniFiles.get_explorer_state().target_window
      local restore = set_option("winhighlight", "Normal:Visual,SignColumn:Visual", { win = target })
      vim.api.nvim_create_autocmd("User", { once = true, pattern = "MiniFilesExplorerClose", callback = restore })
    end,
  })

Screen.Recording.2025-12-16.at.12.17.36.PM.mov

[echasnovski]

This is an interesting idea! Thanks for sharing!

I'd go with a bit more compact solution:

local hl_target_win = function()
  -- Only highlight a window if there is more than one possible target
  local n_win = 0
  for _, win_id in ipairs(vim.api.nvim_tabpage_list_wins(0)) do
    -- Treat only normal windows (not floating) as a target
    local is_target = vim.api.nvim_win_get_config(win_id).relative == ''
    n_win = n_win + (is_target and 1 or 0)
  end
  if n_win == 1 then return end

  -- Temporarily set 'winhighlight' and setup restore after closing explorer
  local target_win_id = MiniFiles.get_explorer_state().target_window
  local winhl_orig = vim.wo[target_win_id].winhighlight
  vim.wo[target_win_id].winhighlight = 'Normal:Visual,SignColumn:Visual'
  local restore = function() vim.wo[target_win_id].winhighlight = winhl_orig end
  vim.api.nvim_create_autocmd('User', { once = true, pattern = 'MiniFilesExplorerClose', callback = restore })
end

local au_opts = { pattern = 'MiniFilesExplorerOpen', callback = hl_target_win, desc = 'Highlight target window' }
vim.api.nvim_create_autocmd('User', au_opts)

Also note that this will not work well with documented example of modifying target window.

Edit: do not use vim.fn.winnr('$') == 1 as a condition for when to highlight since it treats explorer windows themselves as targets (since they are focusable).

[pkazmier]

My original post did not quite work as intended due to the way window local options behave. The previous implementation used the winhighlight to customize the highlight groups in the target window. That option, however, is a window local option, which has the following consequence (from the docs: local-options):

The options local to a window are remembered for each buffer.

Consequently, when the user opened a file in the explorer, our restore function to remove the window local option was applied to the correct window, but it already contained the new file. So when the user switched back to the prior buffer in the same window, it remembered the window highlight options that were previously set and incorrectly highlighted the window.

This new implementation uses highlight namespaces to achieve the originally intended effect. A window can be assigned a highlight namespace, which can define hl groups that take priority over the global hl groups. Like the prior implementation, I save a copy of any previously applied highlight namespace so it can be restored upon exit of the explorer. This version works as expected because the hl namespace is applied to the window regardless of what buffer is contained within.

  -- Create hl namespace to highlight 'mini.files' target window
  local highlight_ns = vim.api.nvim_create_namespace("highlight_minifiles_target")
  vim.api.nvim_set_hl(highlight_ns, "Normal", { link = "Visual" })
  vim.api.nvim_set_hl(highlight_ns, "SignColumn", { link = "Visual" })

  local hl_target_win = function()
    -- Only highlight a window if there is more than one possible target
    local possible_targets = vim
      .iter(vim.api.nvim_tabpage_list_wins(0))
      :filter(function(w) return vim.api.nvim_win_get_config(w).relative == "" end)
      :fold(0, function(acc, _) return acc + 1 end)
    if possible_targets == 1 then return end

    -- Temporarily set a window hl namespace and setup restore after closing explorer
    local target_win_id = MiniFiles.get_explorer_state().target_window
    local orig_hl_ns = vim.api.nvim_get_hl_ns({ winid = target_win_id })
    local restore = function() vim.api.nvim_win_set_hl_ns(target_win_id, orig_hl_ns ~= -1 and orig_hl_ns or 0) end
    vim.api.nvim_win_set_hl_ns(target_win_id, highlight_ns)
    vim.api.nvim_create_autocmd("User", { once = true, pattern = "MiniFilesExplorerClose", callback = restore })
  end

  local au_opts = { pattern = "MiniFilesExplorerOpen", callback = hl_target_win, desc = "Highlight target window" }
  vim.api.nvim_create_autocmd("User", au_opts)