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>

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|'

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;

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)

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:

src/nvim/options.lua

@@ -10713,6 +10713,19 @@ local options = {
       type = 'number',
       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',

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"));
+    }
   }
 }
 

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) {