patch 9.0.0913: only change in current window triggers the WinScrolled event

Problem:    Only a change in the current window triggers the WinScrolled
            event.
Solution:   Trigger WinScrolled if any window scrolled or changed size.
            (issue #11576)
diff --git a/src/testdir/dumps/Test_winscrolled_once_only_1.dump b/src/testdir/dumps/Test_winscrolled_once_only_1.dump
new file mode 100644
index 0000000..56d6401
--- /dev/null
+++ b/src/testdir/dumps/Test_winscrolled_once_only_1.dump
@@ -0,0 +1,10 @@
+|a+0&#ffffff0@2| @26||+1&&>b+0&&@2| @25
+|b@2| @26||+1&&|~+0#4040ff13&| @27
+|~| @28||+1#0000000&|~+0#4040ff13&| @27
+|[+1#0000000&|N|o| |N|a|m|e|]| |[|+|]| @1|1|,|1| @8|A|l@1|||~+0#4040ff13&| @27
+|a+0#0000000&@2| @26||+1&&|~+0#4040ff13&| @27
+|b+0#0000000&@2| @26||+1&&|~+0#4040ff13&| @27
+|~| @28||+1#0000000&|~+0#4040ff13&| @27
+|[+1#0000000&|N|o| |N|a|m|e|]| |[|+|]| @1|1|,|1| @8|A|l@1| |[+3&&|N|o| |N|a|m|e|]| |[|+|]| @1|2|,|1| @7|B|o|t
+|1+0&&| |1|0@2| |[|'|r|o|w|'|,| |[@1|'|c|o|l|'|,| |[@1|'|l|e|a|f|'|,| |1|0@1|2|]|,| |[|'|l|e|a|f|'|,| |1|0@1|1|]@2|,| |[
+|'|l|e|a|f|'|,| |1|0@2|]@2| @44
diff --git a/src/testdir/test_autocmd.vim b/src/testdir/test_autocmd.vim
index 637fdb8..5d3e0ac 100644
--- a/src/testdir/test_autocmd.vim
+++ b/src/testdir/test_autocmd.vim
@@ -407,11 +407,38 @@
   call TermWait(buf)
   call StopVimInTerminal(buf)
 
+  " check the startup script finished to the end
   call assert_equal(['123456'], readfile('Xtestout'))
-
   call delete('Xtestout')
 endfunc
 
+func Test_WinScrolled_once_only()
+  CheckRunVimInTerminal
+
+  let lines =<< trim END
+      set cmdheight=2
+      call setline(1, ['aaa', 'bbb'])
+      let trigger_count = 0
+      func ShowInfo(id)
+        echo g:trigger_count g:winid winlayout()
+      endfunc
+
+      vsplit
+      split
+      " use a timer to show the info after a redraw
+      au WinScrolled * let trigger_count += 1 | let winid = expand('<amatch>') | call timer_start(100, 'ShowInfo')
+      wincmd j
+      wincmd l
+  END
+  call writefile(lines, 'Xtest_winscrolled_once', 'D')
+  let buf = RunVimInTerminal('-S Xtest_winscrolled_once', #{rows: 10, cols: 60, statusoff: 2})
+
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_winscrolled_once_only_1', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
 func Test_WinScrolled_long_wrapped()
   CheckRunVimInTerminal
 
@@ -2916,6 +2943,7 @@
   call assert_fails('set spell spelllang=0', 'E937:')
 
   au! SpellFileMissing
+  set nospell spelllang=en
   bwipe
 endfunc