vim-patch:9.0.0969: matchparen highlight is not updated when switching buffers (#21227)

Problem:    Matchparen highlight is not updated when switching buffers.
Solution:   Listen to the BufLeave and the BufWinEnter autocmd events.
            (closes vim/vim#11626)

28a896f54d

Co-authored-by: Bram Moolenaar <Bram@vim.org>

test/functional/legacy/visual_mode_spec.lua

@@ -1,31 +1,28 @@
 local helpers = require('test.functional.helpers')(after_each)
 
 local Screen = require('test.functional.ui.screen')
-local call = helpers.call
 local clear = helpers.clear
 local feed = helpers.feed
-local feed_command = helpers.feed_command
-local funcs = helpers.funcs
-local meths = helpers.meths
-local eq = helpers.eq
 local exec = helpers.exec
 
-describe('visual line mode', function()
-  local screen
+before_each(clear)
 
+describe('visual line mode', function()
+  -- oldtest: Test_visual_block_scroll()
   it('redraws properly after scrolling with matchparen loaded and scrolloff=1', function()
-    clear{args={'-u', 'NORC'}}
-    screen = Screen.new(30, 7)
+    local screen = Screen.new(30, 7)
     screen:attach()
     screen:set_default_attr_ids({
       [1] = {bold = true},
       [2] = {background = Screen.colors.LightGrey},
     })
 
-    eq(1, meths.get_var('loaded_matchparen'))
-    feed_command('set scrolloff=1')
-    funcs.setline(1, {'a', 'b', 'c', 'd', 'e', '', '{', '}', '{', 'f', 'g', '}'})
-    call('cursor', 5, 1)
+    exec([[
+      source $VIMRUNTIME/plugin/matchparen.vim
+      set scrolloff=1
+      call setline(1, ['a', 'b', 'c', 'd', 'e', '', '{', '}', '{', 'f', 'g', '}'])
+      call cursor(5, 1)
+    ]])
 
     feed('V<c-d><c-d>')
     screen:expect([[
@@ -41,8 +38,8 @@ describe('visual line mode', function()
 end)
 
 describe('visual block mode', function()
+  -- oldtest: Test_visual_block_with_virtualedit()
   it('shows selection correctly with virtualedit=block', function()
-    clear()
     local screen = Screen.new(30, 7)
     screen:set_default_attr_ids({
       [1] = {bold = true},  -- ModeMsg