fix(ui2): avoid ModeChanged in message window #40788

runtime/lua/vim/_core/ui2/messages.lua

@@ -486,7 +486,8 @@ function M.msg_show(kind, content, replace_last, _, append, id, trigger)
       M.cmd.ids, M.cmd.prev_msg = {}, ''
     elseif tgt == 'pager' then
       -- Position cursor at start of first or last message at bottom of window.
-      fn.win_execute(ui.wins.pager, 'norm! ' .. (enter_pager and 'gg0' or 'G0zb'))
+      local lnum = enter_pager and 1 or api.nvim_buf_line_count(ui.bufs.pager)
+      api.nvim_win_set_cursor(ui.wins.pager, { lnum, 0 })
     end
   end
 end
@@ -718,7 +719,7 @@ function M.set_pos(tgt)
         M.dialog_on_key = vim.on_key(dialog_on_key, M.dialog_on_key)
       elseif tgt == 'msg' then
         -- Ensure last line is visible and first line is at top of window.
-        fn.win_execute(ui.wins.msg, 'norm! Gzb')
+        api.nvim_win_set_cursor(ui.wins.msg, { api.nvim_buf_line_count(ui.bufs.msg), 0 })
       elseif tgt == 'pager' and not in_pager then
         enter_pager()
       end

test/functional/ui/messages2_spec.lua

@@ -994,6 +994,19 @@ describe('messages2', function()
     ]])
   end)
 
+  it('msg window timer does not trigger ModeChanged #40780', function()
+    exec_lua(function()
+      require('vim._core.ui2').enable({ msg = { targets = 'msg', msg = { timeout = 50 } } })
+    end)
+    command('let g:modechanged = []')
+    command([[autocmd ModeChanged i:n call add(g:modechanged, copy(v:event))]])
+    command([[echo "a" | echo "b" | startinsert]])
+    screen:sleep(100)
+    t.eq({}, n.eval('g:modechanged'))
+    feed('<Esc>')
+    t.eq({ { old_mode = 'i', new_mode = 'n' } }, n.eval('g:modechanged'))
+  end)
+
   it('configured targets per kind', function()
     exec_lua(function()
       local targets = { echo = 'msg', list_cmd = 'pager', bufwrite = 'cmd', lua_print = 'cmd' }