feat(options): add 'winpinned' to pin a window #39157

Problem:
- Unable to "pin" a window to prevent closing without specifically
  being targeted.
- :fclose closes hidden windows (even before visible windows).

Solution:
- Add 'winpinned' window-local option. When set, window is skipped by
  :fclose and :only. Pin the ui2 cmdline window (which should always be
  visible), so that it is not closed by :only/fclose.
- Skip over hidden (and pinned) windows with :fclose.

Co-authored-by: glepnir <glephunter@gmail.com>

14 files changed, 88 insertions, 9 deletions

diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index ccedbee310..f287b68d29 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -156,7 +156,7 @@ the same range instances now compare equal.
 
 OPTIONS
 
-• todo
+• 'winpinned' prevents window from closing unless specifically targeted.
 
 PERFORMANCE
 
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index f2bca82cc8..de92fc98ff 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -296,6 +296,7 @@ created, thus they behave slightly differently:
 	'winfixbuf'	specific to existing window
 	'winfixheight'	specific to existing window
 	'winfixwidth'	specific to existing window
+	'winpinned'	specific to existing window
 
 Special local buffer options
 
@@ -7626,6 +7627,13 @@ A jump table for the options with a short description can be found at |Q_op|.
 	large number, it will cause errors when opening more than a few
 	windows.  A value of 0 to 12 is reasonable.
 
+				*'winpinned'* *'wp'* *'nowinpinned'* *'nowp'*
+'winpinned' 'wp'	boolean	(default off)
+			local to window  |local-noglobal|
+	If enabled, the window is pinned and will not be closed by |:only|
+	and |:fclose|. Only commands specifically targeting the window can
+	close it.
+
 						*'winwidth'* *'wiw'* *E592*
 'winwidth' 'wiw'	number	(default 20)
 			global
diff --git a/runtime/lua/vim/_core/ui2.lua b/runtime/lua/vim/_core/ui2.lua
index 77ea7f57b3..4c7ceefda0 100644
--- a/runtime/lua/vim/_core/ui2.lua
+++ b/runtime/lua/vim/_core/ui2.lua
@@ -130,6 +130,8 @@ function M.check_targets()
           hl = 'Normal:MsgArea'
         elseif type == 'msg' then
           hl = search_hide
+        elseif type == 'cmd' then
+          api.nvim_set_option_value('winpinned', true, { scope = 'local' })
         end
         api.nvim_set_option_value('winhighlight', hl, { scope = 'local' })
       end)
diff --git a/runtime/lua/vim/_meta/options.gen.lua b/runtime/lua/vim/_meta/options.gen.lua
index c151c448bb..82f53eedc7 100644
--- a/runtime/lua/vim/_meta/options.gen.lua
+++ b/runtime/lua/vim/_meta/options.gen.lua
@@ -8324,6 +8324,16 @@ vim.o.wmw = vim.o.winminwidth
 vim.go.winminwidth = vim.o.winminwidth
 vim.go.wmw = vim.go.winminwidth
 
+--- If enabled, the window is pinned and will not be closed by `:only`
+--- and `:fclose`. Only commands specifically targeting the window can
+--- close it.
+---
+--- @type boolean
+vim.o.winpinned = false
+vim.o.wp = vim.o.winpinned
+vim.wo.winpinned = vim.o.winpinned
+vim.wo.wp = vim.wo.winpinned
+
 --- Minimal number of columns for the current window.  This is not a hard
 --- minimum, Vim will use fewer columns if there is not enough room.  If
 --- the current window is smaller, its size is increased, at the cost of
diff --git a/runtime/scripts/optwin.lua b/runtime/scripts/optwin.lua
index f91cbedc67..6961182cf3 100644
--- a/runtime/scripts/optwin.lua
+++ b/runtime/scripts/optwin.lua
@@ -128,6 +128,7 @@ local options_list = {
     { 'winfixwidth', N_ 'keep the width of the window' },
     { 'winwidth', N_ 'minimal number of columns used for the current window' },
     { 'winminwidth', N_ 'minimal number of columns used for any window' },
+    { 'winpinned', N_ 'prevent closing window with :only and :fclose' },
     { 'helpheight', N_ 'initial height of the help window' },
     { 'previewheight', N_ 'default height for the preview window' },
     { 'previewwindow', N_ 'identifies the preview window' },
diff --git a/src/gen/gen_eval_files.lua b/src/gen/gen_eval_files.lua
index 4609509042..05f2d52fcf 100755
--- a/src/gen/gen_eval_files.lua
+++ b/src/gen/gen_eval_files.lua
@@ -667,6 +667,7 @@ local function option_scope_doc(o)
       'syntax',
       'winfixheight',
       'winfixwidth',
+      'winpinned',
     }, o.full_name)
   then
     r = r .. '  |local-noglobal|'
diff --git a/src/nvim/buffer_defs.h b/src/nvim/buffer_defs.h
index 6b1719cc6e..546d6e5a6a 100644
--- a/src/nvim/buffer_defs.h
+++ b/src/nvim/buffer_defs.h
@@ -148,6 +148,8 @@ typedef struct {
 #define w_p_wfh w_onebuf_opt.wo_wfh    // 'winfixheight'
   int wo_wfw;
 #define w_p_wfw w_onebuf_opt.wo_wfw    // 'winfixwidth'
+  int wo_wp;
+#define w_p_wp w_onebuf_opt.wo_wp    // 'winpinned'
   int wo_pvw;
 #define w_p_pvw w_onebuf_opt.wo_pvw    // 'previewwindow'
   OptInt wo_lhi;
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 34aef2e476..e527b38b6a 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -5329,7 +5329,7 @@ void tabpage_close(int forceit)
     ex_win_close(forceit, curwin, NULL);
   }
   if (!ONE_WINDOW) {
-    close_others(true, forceit);
+    close_others(true, forceit, true);
   }
   if (ONE_WINDOW) {
     ex_win_close(forceit, curwin, NULL);
@@ -5402,7 +5402,7 @@ static void ex_only(exarg_T *eap)
       win_goto(wp);
     }
   }
-  close_others(true, eap->forceit);
+  close_others(true, eap->forceit, false);
 }
 
 static void ex_hide(exarg_T *eap)
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 030702ccaf..51403a0fe6 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -4859,6 +4859,8 @@ void *get_varp_from(vimoption_T *p, buf_T *buf, win_T *win)
     return &(win->w_p_wfh);
   case kOptWinfixwidth:
     return &(win->w_p_wfw);
+  case kOptWinpinned:
+    return &(win->w_p_wp);
   case kOptPreviewwindow:
     return &(win->w_p_pvw);
   case kOptLhistory:
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index 5ec0fe842a..a24da96883 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -10714,6 +10714,19 @@ local options = {
       varname = 'p_wmw',
     },
     {
+      abbreviation = 'wp',
+      defaults = false,
+      desc = [=[
+        If enabled, the window is pinned and will not be closed by |:only|
+        and |:fclose|. Only commands specifically targeting the window can
+        close it.
+      ]=],
+      full_name = 'winpinned',
+      scope = { 'win' },
+      short_desc = N_('prevent closing window with :only and :fclose'),
+      type = 'boolean',
+    },
+    {
       abbreviation = 'wiw',
       cb = 'did_set_winwidth',
       defaults = 20,
diff --git a/src/nvim/window.c b/src/nvim/window.c
index b7d3bce5c5..a82dfa0f80 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -4248,10 +4248,12 @@ static int frame_minwidth(frame_T *topfrp, win_T *next_curwin)
 /// Buffers in the other windows become hidden if 'hidden' is set, or '!' is
 /// used and the buffer was modified.
 ///
-/// Used by ":bdel" and ":only".
+/// Used by ":tabclose" and ":only".
 ///
-/// @param forceit  always hide all other windows
-void close_others(int message, int forceit)
+/// @param message       if true, display error messages
+/// @param forceit       always hide all other windows
+/// @param ignore_pinned if true, also close pinned windows (for :tabclose)
+void close_others(int message, int forceit, bool ignore_pinned)
 {
   win_T *const old_curwin = curwin;
 
@@ -4280,7 +4282,8 @@ void close_others(int message, int forceit)
       curbuf = curwin->w_buffer;
     }
 
-    if (wp == curwin) {                 // don't close current window
+    // don't close current window or pinned windows
+    if (wp == curwin || (wp->w_p_wp && !ignore_pinned)) {
       continue;
     }
 
@@ -4312,7 +4315,17 @@ void close_others(int message, int forceit)
   }
 
   if (message && !ONE_WINDOW) {
-    emsg(_("E445: Other window contains changes"));
+    // Check if remaining windows are non-pinned
+    bool has_non_pinned = false;
+    for (win_T *wp = firstwin; wp != NULL; wp = wp->w_next) {
+      if (wp != curwin && !wp->w_p_wp) {
+        has_non_pinned = true;
+        break;
+      }
+    }
+    if (has_non_pinned) {
+      emsg(_("E445: Other window contains changes"));
+    }
   }
 }
 
diff --git a/src/nvim/winfloat.c b/src/nvim/winfloat.c
index f222f6b17e..e949aaf141 100644
--- a/src/nvim/winfloat.c
+++ b/src/nvim/winfloat.c
@@ -298,6 +298,9 @@ void win_float_remove(bool bang, int count)
 {
   kvec_t(win_T *) float_win_arr = KV_INITIAL_VALUE;
   for (win_T *wp = lastwin; wp && wp->w_floating; wp = wp->w_prev) {
+    if (wp->w_config.hide || wp->w_p_wp) {
+      continue;
+    }
     kv_push(float_win_arr, wp);
   }
   if (float_win_arr.size > 0) {
diff --git a/test/functional/api/window_spec.lua b/test/functional/api/window_spec.lua
index daf0ae8ce1..650a4bf5e3 100644
--- a/test/functional/api/window_spec.lua
+++ b/test/functional/api/window_spec.lua
@@ -3861,4 +3861,28 @@ describe('API/win', function()
       eq(float_win, api.nvim_get_current_win())
     end)
   end)
+
+  it(':fclose and :only skip hidden and pinned windows #36123', function()
+    local cfg = { relative = 'editor', row = 0, col = 0, width = 1, height = 1 }
+    local win1 = api.nvim_open_win(0, false, cfg)
+    command('fclose')
+    eq(false, api.nvim_win_is_valid(win1))
+    cfg.hide = true
+    win1 = api.nvim_open_win(0, false, cfg)
+    cfg.hide, cfg.focusable = false, false
+    local win2 = api.nvim_open_win(0, false, cfg)
+    command('fclose')
+    eq(true, api.nvim_win_is_valid(win1))
+    eq(false, api.nvim_win_is_valid(win2))
+    api.nvim_win_set_config(win1, { hide = false })
+    api.nvim_set_option_value('winpinned', true, { win = win1, scope = 'local' })
+    win2 = api.nvim_open_win(0, false, { split = 'right' })
+    api.nvim_set_option_value('winpinned', true, { win = win2, scope = 'local' })
+    command('only')
+    eq(true, api.nvim_win_is_valid(win1))
+    eq(true, api.nvim_win_is_valid(win2))
+    local tab2 = api.nvim_open_tabpage(0, false, {})
+    command('tabclose')
+    eq(tab2, api.nvim_get_current_tabpage())
+  end)
 end)
diff --git a/test/functional/ui/messages2_spec.lua b/test/functional/ui/messages2_spec.lua
index c3cf060bc9..f030ca8692 100644
--- a/test/functional/ui/messages2_spec.lua
+++ b/test/functional/ui/messages2_spec.lua
@@ -432,7 +432,7 @@ describe('messages2', function()
     screen:expect([[
       ^                                                     |
       {1:~                                                    }|*12
-                                                           |
+      foo [+1]                                             |
     ]])
   end)