diff --git a/src/evalfunc.c b/src/evalfunc.c
index 169f972..627ebb0 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -2330,6 +2330,10 @@
 			ret_void,	    f_test_gui_drop_files},
     {"test_gui_mouse_event",	5, 5, 0,    arg5_number,
 			ret_void,	    f_test_gui_mouse_event},
+    {"test_gui_tabline_event",	1, 1, 0,    arg1_number,
+			ret_bool,	    f_test_gui_tabline_event},
+    {"test_gui_tabmenu_event",	2, 2, 0,    arg2_number,
+			ret_void,	    f_test_gui_tabmenu_event},
     {"test_ignore_error", 1, 1, FEARG_1,    arg1_string,
 			ret_void,	    f_test_ignore_error},
     {"test_null_blob",	0, 0, 0,	    NULL,
diff --git a/src/normal.c b/src/normal.c
index b6c59d3..e69c141 100644
--- a/src/normal.c
+++ b/src/normal.c
@@ -2801,8 +2801,9 @@
 }
 
 /*
- * Get the count specified after a 'z' command. Returns TRUE to process
- * the 'z' command and FALSE to skip it.
+ * Get the count specified after a 'z' command. Only the 'z<CR>', 'zl', 'zh',
+ * 'z<Left>', and 'z<Right>' commands accept a count after 'z'.
+ * Returns TRUE to process the 'z' command and FALSE to skip it.
  */
     static int
 nv_z_get_count(cmdarg_T *cap, int *nchar_arg)
diff --git a/src/proto/testing.pro b/src/proto/testing.pro
index 0d4ff49..b432b4f 100644
--- a/src/proto/testing.pro
+++ b/src/proto/testing.pro
@@ -35,6 +35,8 @@
 void f_test_scrollbar(typval_T *argvars, typval_T *rettv);
 void f_test_setmouse(typval_T *argvars, typval_T *rettv);
 void f_test_gui_mouse_event(typval_T *argvars, typval_T *rettv);
+void f_test_gui_tabline_event(typval_T *argvars, typval_T *rettv);
+void f_test_gui_tabmenu_event(typval_T *argvars, typval_T *rettv);
 void f_test_settime(typval_T *argvars, typval_T *rettv);
 void f_test_gui_drop_files(typval_T *argvars, typval_T *rettv);
 /* vim: set ft=c : */
diff --git a/src/testdir/test_diffmode.vim b/src/testdir/test_diffmode.vim
index 57115de..ea217d9 100644
--- a/src/testdir/test_diffmode.vim
+++ b/src/testdir/test_diffmode.vim
@@ -1464,4 +1464,50 @@
   set diffopt&vim
 endfunc
 
+" Test for using the 'zi' command to invert 'foldenable' in diff windows (test
+" for the issue fixed by patch 6.2.317)
+func Test_diff_foldinvert()
+  %bw!
+  edit Xfile1
+  new Xfile2
+  new Xfile3
+  windo diffthis
+  " open a non-diff window
+  botright new
+  1wincmd w
+  call assert_true(getwinvar(1, '&foldenable'))
+  call assert_true(getwinvar(2, '&foldenable'))
+  call assert_true(getwinvar(3, '&foldenable'))
+  normal zi
+  call assert_false(getwinvar(1, '&foldenable'))
+  call assert_false(getwinvar(2, '&foldenable'))
+  call assert_false(getwinvar(3, '&foldenable'))
+  normal zi
+  call assert_true(getwinvar(1, '&foldenable'))
+  call assert_true(getwinvar(2, '&foldenable'))
+  call assert_true(getwinvar(3, '&foldenable'))
+
+  " If the current window has 'noscrollbind', then 'zi' should not change
+  " 'foldenable' in other windows.
+  1wincmd w
+  set noscrollbind
+  normal zi
+  call assert_false(getwinvar(1, '&foldenable'))
+  call assert_true(getwinvar(2, '&foldenable'))
+  call assert_true(getwinvar(3, '&foldenable'))
+
+  " 'zi' should not change the 'foldenable' for windows with 'noscrollbind'
+  1wincmd w
+  set scrollbind
+  normal zi
+  call setwinvar(2, '&scrollbind', v:false)
+  normal zi
+  call assert_false(getwinvar(1, '&foldenable'))
+  call assert_true(getwinvar(2, '&foldenable'))
+  call assert_false(getwinvar(3, '&foldenable'))
+
+  %bw!
+  set scrollbind&
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/testdir/test_gui.vim b/src/testdir/test_gui.vim
index 9055284..aeacb31 100644
--- a/src/testdir/test_gui.vim
+++ b/src/testdir/test_gui.vim
@@ -1266,4 +1266,57 @@
   cunmap <buffer> <F4>
 endfunc
 
+" Test for generating a GUI tabline event to select a tab page
+func Test_gui_tabline_event()
+  %bw!
+  edit Xfile1
+  tabedit Xfile2
+  tabedit Xfile3
+
+  tabfirst
+  call assert_equal(v:true, test_gui_tabline_event(2))
+  call feedkeys("y", "Lx!")
+  call assert_equal(2, tabpagenr())
+  call assert_equal(v:true, test_gui_tabline_event(3))
+  call feedkeys("y", "Lx!")
+  call assert_equal(3, tabpagenr())
+  call assert_equal(v:false, test_gui_tabline_event(3))
+
+  " From the cmdline window, tabline event should not be handled
+  call feedkeys("q::let t = test_gui_tabline_event(2)\<CR>:q\<CR>", 'x!')
+  call assert_equal(v:false, t)
+
+  %bw!
+endfunc
+
+" Test for generating a GUI tabline menu event to execute an action
+func Test_gui_tabmenu_event()
+  %bw!
+
+  " Try to close the last tab page
+  call test_gui_tabmenu_event(1, 1)
+  call feedkeys("y", "Lx!")
+
+  edit Xfile1
+  tabedit Xfile2
+  call test_gui_tabmenu_event(1, 1)
+  call feedkeys("y", "Lx!")
+  call assert_equal(1, tabpagenr('$'))
+  call assert_equal('Xfile2', bufname())
+
+  call test_gui_tabmenu_event(1, 2)
+  call feedkeys("y", "Lx!")
+  call assert_equal(2, tabpagenr('$'))
+
+  " If tabnr is 0, then the current tabpage should be used.
+  call test_gui_tabmenu_event(0, 2)
+  call feedkeys("y", "Lx!")
+  call assert_equal(3, tabpagenr('$'))
+  call test_gui_tabmenu_event(0, 1)
+  call feedkeys("y", "Lx!")
+  call assert_equal(2, tabpagenr('$'))
+
+  %bw!
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/src/testdir/test_normal.vim b/src/testdir/test_normal.vim
index 4a09964..9fcc9fd 100644
--- a/src/testdir/test_normal.vim
+++ b/src/testdir/test_normal.vim
@@ -891,6 +891,7 @@
 func Test_normal_z_error()
   call assert_beeps('normal! z2p')
   call assert_beeps('normal! zq')
+  call assert_beeps('normal! cz1')
 endfunc
 
 func Test_normal15_z_scroll_vert()
@@ -930,7 +931,7 @@
   call assert_equal(10, winheight(0))
   exe "norm! z12\<cr>"
   call assert_equal(12, winheight(0))
-  exe "norm! z10\<cr>"
+  exe "norm! z15\<Del>0\<cr>"
   call assert_equal(10, winheight(0))
 
   " Test for z.
diff --git a/src/testing.c b/src/testing.c
index 4d2a942..675eaa2 100644
--- a/src/testing.c
+++ b/src/testing.c
@@ -1340,6 +1340,40 @@
 }
 
     void
+f_test_gui_tabline_event(typval_T *argvars UNUSED, typval_T *rettv UNUSED)
+{
+# ifdef FEAT_GUI
+    int	tabnr;
+
+    if (check_for_number_arg(argvars, 0) == FAIL)
+	return;
+
+    tabnr = tv_get_number(&argvars[0]);
+
+    rettv->v_type = VAR_BOOL;
+    rettv->vval.v_number = send_tabline_event(tabnr);
+# endif
+}
+
+    void
+f_test_gui_tabmenu_event(typval_T *argvars UNUSED, typval_T *rettv UNUSED)
+{
+# ifdef FEAT_GUI
+    int	tabnr;
+    int	event;
+
+    if (check_for_number_arg(argvars, 0) == FAIL
+	    || check_for_number_arg(argvars, 1) == FAIL)
+	return;
+
+    tabnr = tv_get_number(&argvars[0]);
+    event = tv_get_number(&argvars[1]);
+
+    send_tabline_menu_event(tabnr, event);
+# endif
+}
+
+    void
 f_test_settime(typval_T *argvars, typval_T *rettv UNUSED)
 {
     if (in_vim9script() && check_for_number_arg(argvars, 0) == FAIL)
diff --git a/src/version.c b/src/version.c
index e77826c..e3a9715 100644
--- a/src/version.c
+++ b/src/version.c
@@ -751,6 +751,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    4228,
+/**/
     4227,
 /**/
     4226,