From dff3028fe7dfbfc82c57e0130a43795f645a148c Mon Sep 17 00:00:00 2001
From: Luuk van Baal <luukvbaal@gmail.com>
Date: Sun, 15 Mar 2026 01:25:10 +0100
Subject: [PATCH] fix(ui2): move windows to current tabpage

Problem:  Windows are closed and re-opened after changing tabpage (and
          might be removed from the current tabpage after 094b297a).
Solution: Ensure windows are on the current tabpage by moving them.
---
 runtime/lua/vim/_core/ui2.lua | 36 +++++++++++------------------------
 1 file changed, 11 insertions(+), 25 deletions(-)

diff --git a/runtime/lua/vim/_core/ui2.lua b/runtime/lua/vim/_core/ui2.lua
index 1414eb75e7..b495b7355c 100644
--- a/runtime/lua/vim/_core/ui2.lua
+++ b/runtime/lua/vim/_core/ui2.lua
@@ -51,22 +51,17 @@ local M = {
   },
 }
 
-local tab = 0
 ---Ensure target buffers and windows are still valid.
 function M.check_targets()
   local curtab = api.nvim_get_current_tabpage()
   for i, type in ipairs({ 'cmd', 'dialog', 'msg', 'pager' }) do
-    local oldbuf = api.nvim_buf_is_valid(M.bufs[type]) and M.bufs[type]
-    local oldwin, setopt = api.nvim_win_is_valid(M.wins[type]) and M.wins[type], not oldbuf
-    M.bufs[type] = oldbuf or api.nvim_create_buf(false, false)
+    local buf = api.nvim_buf_is_valid(M.bufs[type]) and M.bufs[type]
+    local win = api.nvim_win_is_valid(M.wins[type]) and M.wins[type]
+    local floating = win and api.nvim_win_get_config(win).zindex
+    local setopt = not buf or not win or not floating
+    M.bufs[type] = buf or api.nvim_create_buf(false, false)
 
-    if tab ~= curtab and oldwin then
-      -- Ensure dynamically set window configuration (M.msg.set_pos()) is copied
-      -- over when switching tabpage. TODO: move to tabpage instead after #35816.
-      M.wins[type] = api.nvim_open_win(M.bufs[type], false, api.nvim_win_get_config(oldwin))
-      api.nvim_win_close(oldwin, true)
-      setopt = true
-    elseif not oldwin or not api.nvim_win_get_config(M.wins[type]).zindex then
+    if not win or not floating then
       -- Open a new window when closed or no longer floating (e.g. wincmd J).
       local cfg = { col = 0, row = 1, width = 10000, height = 1, mouse = false, noautocmd = true }
       cfg.focusable = false
@@ -80,9 +75,11 @@ function M.check_targets()
       -- kZIndexMessages < cmd zindex < kZIndexCmdlinePopupMenu (grid_defs.h), pager below others.
       cfg.zindex = 201 - i
       M.wins[type] = api.nvim_open_win(M.bufs[type], false, cfg)
-      setopt = true
-    elseif api.nvim_win_get_buf(M.wins[type]) ~= M.bufs[type] then
-      api.nvim_win_set_buf(M.wins[type], M.bufs[type])
+    elseif api.nvim_win_get_tabpage(M.wins[type]) ~= curtab then
+      api.nvim_win_set_config(M.wins[type], { win = api.nvim_tabpage_get_win(curtab) })
+    end
+    if win and floating and api.nvim_win_get_buf(win) ~= M.bufs[type] then
+      api.nvim_win_set_buf(win, M.bufs[type])
       setopt = true
     end
 
@@ -125,7 +122,6 @@ function M.check_targets()
       end
     end
   end
-  tab = curtab
 end
 
 local function ui_callback(redraw_msg, event, ...)
@@ -221,16 +217,6 @@ function M.enable(opts)
     end,
     desc = 'Set cmdline and message window dimensions after shell resize or tabpage change.',
   })
-
-  api.nvim_create_autocmd('WinEnter', {
-    callback = function()
-      local win = api.nvim_get_current_win()
-      if vim.tbl_contains(M.wins, win) and api.nvim_win_get_config(win).hide then
-        vim.cmd.wincmd('p')
-      end
-    end,
-    desc = 'Make sure hidden UI window is never current.',
-  })
 end
 
 return M