Merge pull request #23320 from luukvbaal/smoothscroll

feat(ui): add 'smoothscroll' option

14 files changed, 1608 insertions, 44 deletions

diff --git a/test/functional/legacy/display_spec.lua b/test/functional/legacy/display_spec.lua
index f9b78f5dcd..4952a5c4fe 100644
--- a/test/functional/legacy/display_spec.lua
+++ b/test/functional/legacy/display_spec.lua
@@ -194,4 +194,51 @@ describe('display', function()
   it('display "lastline" works correctly with multibyte fillchar', function()
     run_test_display_lastline(true)
   end)
+
+  -- oldtest: Test_display_long_lastline
+  it('display "lastline" shows correct text when end of wrapped line is deleted', function()
+    local screen = Screen.new(35, 14)
+    screen:attach()
+    exec([[
+      set display=lastline scrolloff=5
+      call setline(1, [
+        \'aaaaa'->repeat(100),
+        \'bbbbb '->repeat(7) .. 'ccccc '->repeat(7) .. 'ddddd '->repeat(7)
+      \])
+    ]])
+    feed('482|')
+    screen:expect([[
+      <<<aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaa^aaaaaaaaa|
+      aaaaaaaaaa                         |
+                                         |
+    ]])
+    feed('D')
+    screen:expect([[
+      <<<aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa|
+      aaaaaaaaaaaaaaaaaaaaaaaaa^a         |
+      bbbbb bbbbb bbbbb bbbbb bbbbb bb@@@|
+                                         |
+    ]])
+  end)
 end)
diff --git a/test/functional/legacy/scroll_opt_spec.lua b/test/functional/legacy/scroll_opt_spec.lua
new file mode 100644
index 0000000000..b00ff0bc7a
--- /dev/null
+++ b/test/functional/legacy/scroll_opt_spec.lua
@@ -0,0 +1,777 @@
+local helpers = require('test.functional.helpers')(after_each)
+local Screen = require('test.functional.ui.screen')
+local clear = helpers.clear
+local exec = helpers.exec
+local feed = helpers.feed
+
+before_each(clear)
+
+describe('smoothscroll', function()
+  local screen
+
+  before_each(function()
+    screen = Screen.new(40, 12)
+    screen:attach()
+  end)
+
+  -- oldtest: Test_CtrlE_CtrlY_stop_at_end()
+  it('disabled does not break <C-E> and <C-Y> stop at end', function()
+    exec([[
+      enew
+      call setline(1, ['one', 'two'])
+      set number
+    ]])
+    feed('<C-Y>')
+    screen:expect({any = "  1 ^one"})
+    feed('<C-E><C-E><C-E>')
+    screen:expect({any = "  2 ^two"})
+  end)
+
+  -- oldtest: Test_smoothscroll_CtrlE_CtrlY()
+  it('works with <C-E> and <C-E>', function()
+    exec([[
+      call setline(1, [ 'line one', 'word '->repeat(20), 'line three', 'long word '->repeat(7), 'line', 'line', 'line', ])
+      set smoothscroll scrolloff=5
+      :5
+    ]])
+    local s1 = [[
+      word word word word word word word word |
+      word word word word word word word word |
+      word word word word                     |
+      line three                              |
+      long word long word long word long word |
+      long word long word long word           |
+      ^line                                    |
+      line                                    |
+      line                                    |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]]
+    local s2 = [[
+      <<<d word word word word word word word |
+      word word word word                     |
+      line three                              |
+      long word long word long word long word |
+      long word long word long word           |
+      ^line                                    |
+      line                                    |
+      line                                    |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]]
+    local s3 = [[
+      <<<d word word word                     |
+      line three                              |
+      long word long word long word long word |
+      long word long word long word           |
+      ^line                                    |
+      line                                    |
+      line                                    |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]]
+    local s4 = [[
+      line three                              |
+      long word long word long word long word |
+      long word long word long word           |
+      line                                    |
+      line                                    |
+      ^line                                    |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]]
+    local s5 = [[
+      <<<d word word word                     |
+      line three                              |
+      long word long word long word long word |
+      long word long word long word           |
+      line                                    |
+      line                                    |
+      ^line                                    |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]]
+    local s6 = [[
+      <<<d word word word word word word word |
+      word word word word                     |
+      line three                              |
+      long word long word long word long word |
+      long word long word long word           |
+      line                                    |
+      line                                    |
+      ^line                                    |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]]
+    local s7 = [[
+      word word word word word word word word |
+      word word word word word word word word |
+      word word word word                     |
+      line three                              |
+      long word long word long word long word |
+      long word long word long word           |
+      line                                    |
+      line                                    |
+      ^line                                    |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]]
+    local s8 = [[
+      line one                                |
+      word word word word word word word word |
+      word word word word word word word word |
+      word word word word                     |
+      line three                              |
+      long word long word long word long word |
+      long word long word long word           |
+      line                                    |
+      line                                    |
+      ^line                                    |
+      ~                                       |
+                                              |
+    ]]
+    feed('<C-E>')
+    screen:expect(s1)
+    feed('<C-E>')
+    screen:expect(s2)
+    feed('<C-E>')
+    screen:expect(s3)
+    feed('<C-E>')
+    screen:expect(s4)
+    feed('<C-Y>')
+    screen:expect(s5)
+    feed('<C-Y>')
+    screen:expect(s6)
+    feed('<C-Y>')
+    screen:expect(s7)
+    feed('<C-Y>')
+    screen:expect(s8)
+    exec('set foldmethod=indent')
+    -- move the cursor so we can reuse the same dumps
+    feed('5G<C-E>')
+    screen:expect(s1)
+    feed('<C-E>')
+    screen:expect(s2)
+    feed('7G<C-Y>')
+    screen:expect(s7)
+    feed('<C-Y>')
+    screen:expect(s8)
+  end)
+
+  -- oldtest: Test_smoothscroll_number()
+  it("works 'number' and 'cpo'+=n", function()
+    exec([[
+      call setline(1, [ 'one ' .. 'word '->repeat(20), 'two ' .. 'long word '->repeat(7), 'line', 'line', 'line', ])
+      set smoothscroll scrolloff=5
+      set number cpo+=n
+      :3
+      func g:DoRel()
+        set number relativenumber scrolloff=0
+        :%del
+        call setline(1, [ 'one', 'very long text '->repeat(12), 'three', ])
+        exe "normal 2Gzt\<C-E>"
+      endfunc
+    ]])
+    screen:expect([[
+        1 one word word word word word word wo|
+      rd word word word word word word word wo|
+      rd word word word word word             |
+        2 two long word long word long word lo|
+      ng word long word long word long word   |
+        3 ^line                                |
+        4 line                                |
+        5 line                                |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    feed('<C-E>')
+    screen:expect([[
+      <<<word word word word word word word wo|
+      rd word word word word word             |
+        2 two long word long word long word lo|
+      ng word long word long word long word   |
+        3 ^line                                |
+        4 line                                |
+        5 line                                |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    feed('<C-E>')
+    screen:expect([[
+      <<<word word word word word             |
+        2 two long word long word long word lo|
+      ng word long word long word long word   |
+        3 ^line                                |
+        4 line                                |
+        5 line                                |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    exec('set cpo-=n')
+    screen:expect([[
+      <<< d word word word word word word     |
+        2 two long word long word long word lo|
+          ng word long word long word long wor|
+          d                                   |
+        3 ^line                                |
+        4 line                                |
+        5 line                                |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    feed('<C-Y>')
+    screen:expect([[
+      <<< rd word word word word word word wor|
+          d word word word word word word     |
+        2 two long word long word long word lo|
+          ng word long word long word long wor|
+          d                                   |
+        3 ^line                                |
+        4 line                                |
+        5 line                                |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    feed('<C-Y>')
+    screen:expect([[
+        1 one word word word word word word wo|
+          rd word word word word word word wor|
+          d word word word word word word     |
+        2 two long word long word long word lo|
+          ng word long word long word long wor|
+          d                                   |
+        3 ^line                                |
+        4 line                                |
+        5 line                                |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    exec('call DoRel()')
+    screen:expect([[
+      2<<<^ong text very long text very long te|
+          xt very long text very long text ver|
+          y long text very long text very long|
+           text very long text very long text |
+        1 three                               |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      --No lines in buffer--                  |
+    ]])
+  end)
+
+  -- oldtest: Test_smoothscroll_list()
+  it("works with list mode", function()
+    screen:try_resize(40, 8)
+    exec([[
+      set smoothscroll scrolloff=0
+      set list
+      call setline(1, [ 'one', 'very long text '->repeat(12), 'three', ])
+      exe "normal 2Gzt\<C-E>"
+    ]])
+    screen:expect([[
+      <<<t very long text very long text very |
+      ^long text very long text very long text |
+      very long text very long text very long |
+      text very long text-                    |
+      three                                   |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    exec('set listchars+=precedes:#')
+    screen:expect([[
+      #ext very long text very long text very |
+      ^long text very long text very long text |
+      very long text very long text very long |
+      text very long text-                    |
+      three                                   |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+  end)
+
+  -- oldtest: Test_smoothscroll_diff_mode()
+  it("works with diff mode", function()
+    screen:try_resize(40, 8)
+    exec([[
+      let text = 'just some text here'
+      call setline(1, text)
+      set smoothscroll
+      diffthis
+      new
+      call setline(1, text)
+      set smoothscroll
+      diffthis
+    ]])
+    screen:expect([[
+      - ^just some text here                   |
+      ~                                       |
+      ~                                       |
+      [No Name] [+]                           |
+      - just some text here                   |
+      ~                                       |
+      [No Name] [+]                           |
+                                              |
+    ]])
+    feed('<C-Y>')
+    screen:expect_unchanged()
+    feed('<C-E>')
+    screen:expect_unchanged()
+  end)
+
+  -- oldtest: Test_smoothscroll_wrap_scrolloff_zero()
+  it("works with zero 'scrolloff'", function()
+    screen:try_resize(40, 8)
+    exec([[
+      call setline(1, ['Line' .. (' with some text'->repeat(7))]->repeat(7))
+      set smoothscroll scrolloff=0 display=
+      :3
+    ]])
+    screen:expect([[
+      <<<h some text with some text           |
+      Line with some text with some text with |
+      some text with some text with some text |
+      with some text with some text           |
+      ^Line with some text with some text with |
+      some text with some text with some text |
+      with some text with some text           |
+                                              |
+    ]])
+    feed('j')
+    screen:expect_unchanged()
+    -- moving cursor down - whole bottom line shows
+    feed('<C-E>j')
+    screen:expect_unchanged()
+    feed('G')
+    screen:expect_unchanged()
+    -- moving cursor up right after the >>> marker - no need to show whole line
+    feed('2gj3l2k')
+    screen:expect([[
+      <<<^h some text with some text           |
+      Line with some text with some text with |
+      some text with some text with some text |
+      with some text with some text           |
+      Line with some text with some text with |
+      some text with some text with some text |
+      with some text with some text           |
+                                              |
+    ]])
+    -- moving cursor up where the >>> marker is - whole top line shows
+    feed('2j02k')
+    screen:expect([[
+      ^Line with some text with some text with |
+      some text with some text with some text |
+      with some text with some text           |
+      Line with some text with some text with |
+      some text with some text with some text |
+      with some text with some text           |
+      @                                       |
+                                              |
+    ]])
+  end)
+
+  -- oldtest: Test_smoothscroll_wrap_long_line()
+  it("adjusts the cursor position in a long line", function()
+    screen:try_resize(40, 6)
+    exec([[
+      call setline(1, ['one', 'two', 'Line' .. (' with lots of text'->repeat(30)) .. ' end', 'four'])
+      set smoothscroll scrolloff=0
+      normal 3G10|zt
+    ]])
+    -- scrolling up, cursor moves screen line down
+    screen:expect([[
+      Line with^ lots of text with lots of text|
+       with lots of text with lots of text wit|
+      h lots of text with lots of text with lo|
+      ts of text with lots of text with lots o|
+      f text with lots of text with lots of te|
+                                              |
+    ]])
+    feed('<C-E>')
+    screen:expect([[
+      <<<th lot^s of text with lots of text wit|
+      h lots of text with lots of text with lo|
+      ts of text with lots of text with lots o|
+      f text with lots of text with lots of te|
+      xt with lots of text with lots of text w|
+                                              |
+    ]])
+    feed('5<C-E>')
+    screen:expect([[
+      <<< lots ^of text with lots of text with |
+      lots of text with lots of text with lots|
+       of text with lots of text with lots of |
+      text with lots of text with lots of text|
+       with lots of text with lots of text wit|
+                                              |
+    ]])
+    -- scrolling down, cursor moves screen line up
+    feed('5<C-Y>')
+    screen:expect([[
+      <<<th lots of text with lots of text wit|
+      h lots of text with lots of text with lo|
+      ts of text with lots of text with lots o|
+      f text with lots of text with lots of te|
+      xt with l^ots of text with lots of text w|
+                                              |
+    ]])
+    feed('<C-Y>')
+    screen:expect([[
+      Line with lots of text with lots of text|
+       with lots of text with lots of text wit|
+      h lots of text with lots of text with lo|
+      ts of text with lots of text with lots o|
+      f text wi^th lots of text with lots of te|
+                                              |
+    ]])
+    -- 'scrolloff' set to 1, scrolling up, cursor moves screen line down
+    exec('set scrolloff=1')
+    feed('10|<C-E>')
+    screen:expect([[
+      <<<th lots of text with lots of text wit|
+      h lots of^ text with lots of text with lo|
+      ts of text with lots of text with lots o|
+      f text with lots of text with lots of te|
+      xt with lots of text with lots of text w|
+                                              |
+    ]])
+    -- 'scrolloff' set to 1, scrolling down, cursor moves screen line up
+    feed('<C-E>gjgj<C-Y>')
+    screen:expect([[
+      <<<th lots of text with lots of text wit|
+      h lots of text with lots of text with lo|
+      ts of text with lots of text with lots o|
+      f text wi^th lots of text with lots of te|
+      xt with lots of text with lots of text w|
+                                              |
+    ]])
+    -- 'scrolloff' set to 2, scrolling up, cursor moves screen line down
+    exec('set scrolloff=2')
+    feed('10|<C-E>')
+    screen:expect([[
+      <<<th lots of text with lots of text wit|
+      h lots of text with lots of text with lo|
+      ts of tex^t with lots of text with lots o|
+      f text with lots of text with lots of te|
+      xt with lots of text with lots of text w|
+                                              |
+    ]])
+    -- 'scrolloff' set to 2, scrolling down, cursor moves screen line up
+    feed('<C-E>gj<C-Y>')
+    screen:expect_unchanged()
+    -- 'scrolloff' set to 0, move cursor down one line. Cursor should move properly,
+    -- and since this is a really long line, it will be put on top of the screen.
+    exec('set scrolloff=0')
+    feed('0j')
+    screen:expect([[
+      <<<of text with lots of text with lots o|
+      f text with lots of text end            |
+      ^four                                    |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    -- Test zt/zz/zb that they work properly when a long line is above it
+    feed('zb')
+    screen:expect([[
+      <<<th lots of text with lots of text wit|
+      h lots of text with lots of text with lo|
+      ts of text with lots of text with lots o|
+      f text with lots of text end            |
+      ^four                                    |
+                                              |
+    ]])
+    feed('zz')
+    screen:expect([[
+      <<<of text with lots of text with lots o|
+      f text with lots of text end            |
+      ^four                                    |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    feed('zt')
+    screen:expect([[
+      ^four                                    |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    -- Repeat the step and move the cursor down again.
+    -- This time, use a shorter long line that is barely long enough to span more
+    -- than one window. Note that the cursor is at the bottom this time because
+    -- Vim prefers to do so if we are scrolling a few lines only.
+    exec("call setline(1, ['one', 'two', 'Line' .. (' with lots of text'->repeat(10)) .. ' end', 'four'])")
+    feed('3Gztj')
+    screen:expect([[
+      <<<th lots of text with lots of text wit|
+      h lots of text with lots of text with lo|
+      ts of text with lots of text with lots o|
+      f text with lots of text end            |
+      ^four                                    |
+                                              |
+    ]])
+    -- Repeat the step but this time start it when the line is smooth-scrolled by
+    -- one line. This tests that the offset calculation is still correct and
+    -- still end up scrolling down to the next line with cursor at bottom of
+    -- screen.
+    feed('3Gzt<C-E>j')
+    screen:expect([[
+      <<<th lots of text with lots of text wit|
+      h lots of text with lots of text with lo|
+      ts of text with lots of text with lots o|
+      f text with lots of text end            |
+      fou^r                                    |
+                                              |
+    ]])
+  end)
+
+  -- oldtest: Test_smoothscroll_one_long_line()
+  it("scrolls correctly when moving the cursor", function()
+    screen:try_resize(40, 6)
+    exec([[
+      call setline(1, 'with lots of text '->repeat(7))
+      set smoothscroll scrolloff=0
+    ]])
+    local s1 = [[
+      ^with lots of text with lots of text with|
+       lots of text with lots of text with lot|
+      s of text with lots of text with lots of|
+       text                                   |
+      ~                                       |
+                                              |
+    ]]
+    screen:expect(s1)
+    feed('<C-E>')
+    screen:expect([[
+      <<<ts of text with lots of text with lot|
+      ^s of text with lots of text with lots of|
+       text                                   |
+      ~                                       |
+      ~                                       |
+                                              |
+    ]])
+    feed('0')
+    screen:expect(s1)
+  end)
+
+  -- oldtest: Test_smoothscroll_long_line_showbreak()
+  it("cursor is not one screen line too far down", function()
+    screen:try_resize(40, 6)
+    -- a line that spans four screen lines
+    exec("call setline(1, 'with lots of text in one line '->repeat(6))")
+    exec('set smoothscroll scrolloff=0 showbreak=+++\\ ')
+    local s1 = [[
+      ^with lots of text in one line with lots |
+      +++ of text in one line with lots of tex|
+      +++ t in one line with lots of text in o|
+      +++ ne line with lots of text in one lin|
+      +++ e with lots of text in one line     |
+                                              |
+    ]]
+    screen:expect(s1)
+    feed('<C-E>')
+    screen:expect([[
+      +++ ^of text in one line with lots of tex|
+      +++ t in one line with lots of text in o|
+      +++ ne line with lots of text in one lin|
+      +++ e with lots of text in one line     |
+      ~                                       |
+                                              |
+    ]])
+    feed('0')
+    screen:expect(s1)
+  end)
+
+  -- oldtest: Test_smoothscroll_zero_width()
+  it("does not divide by zero with a narrow window", function()
+    screen:try_resize(12, 2)
+    screen:set_default_attr_ids({
+      [1] = {foreground = Screen.colors.Brown},
+      [2] = {foreground = Screen.colors.Blue1, bold = true},
+    })
+    exec([[
+      call setline(1, ['a'->repeat(100)])
+      set wrap smoothscroll number laststatus=0
+      wincmd v
+      wincmd v
+      wincmd v
+      wincmd v
+    ]])
+    screen:expect([[
+      {1:  1^ }│{1: }│{1: }│{1: }│{1: }|
+                  |
+    ]])
+    feed('llllllllll<C-W>o')
+    screen:expect([[
+      {2:<<<}{1: }aa^aaaaaa|
+                  |
+    ]])
+  end)
+
+  it("works with virt_lines above and below", function()
+    screen:try_resize(55, 7)
+    exec([=[
+      call setline(1, ['Line' .. (' with some text'->repeat(7))]->repeat(3))
+      set smoothscroll
+      let ns = nvim_create_namespace('')
+      call nvim_buf_set_extmark(0, ns, 0, 0, {'virt_lines':[[['virt_below1']]]})
+      call nvim_buf_set_extmark(0, ns, 1, 0, {'virt_lines':[[['virt_above1']]],'virt_lines_above':1})
+      call nvim_buf_set_extmark(0, ns, 1, 0, {'virt_lines':[[['virt_below2']]]})
+      call nvim_buf_set_extmark(0, ns, 2, 0, {'virt_lines':[[['virt_above2']]],'virt_lines_above':1})
+      norm ggL
+    ]=])
+    screen:expect([[
+      Line with some text with some text with some text with |
+      some text with some text with some text with some text |
+      virt_below1                                            |
+      virt_above1                                            |
+      ^Line with some text with some text with some text with |
+      some text with some text with some text with some text |
+                                                             |
+    ]])
+    feed('<C-E>')
+    screen:expect([[
+      <<<e text with some text with some text with some text |
+      virt_below1                                            |
+      virt_above1                                            |
+      ^Line with some text with some text with some text with |
+      some text with some text with some text with some text |
+      virt_below2                                            |
+                                                             |
+    ]])
+    feed('<C-E>')
+    screen:expect([[
+      virt_below1                                            |
+      virt_above1                                            |
+      ^Line with some text with some text with some text with |
+      some text with some text with some text with some text |
+      virt_below2                                            |
+      virt_above2                                            |
+                                                             |
+    ]])
+    feed('<C-E>')
+    screen:expect([[
+      virt_above1                                            |
+      ^Line with some text with some text with some text with |
+      some text with some text with some text with some text |
+      virt_below2                                            |
+      virt_above2                                            |
+      Line with some text with some text with some text wi@@@|
+                                                             |
+    ]])
+    feed('<C-E>')
+    screen:expect([[
+      ^Line with some text with some text with some text with |
+      some text with some text with some text with some text |
+      virt_below2                                            |
+      virt_above2                                            |
+      Line with some text with some text with some text with |
+      some text with some text with some text with some text |
+                                                             |
+    ]])
+    feed('<C-E>')
+    screen:expect([[
+      <<<e text with some text with some text with some tex^t |
+      virt_below2                                            |
+      virt_above2                                            |
+      Line with some text with some text with some text with |
+      some text with some text with some text with some text |
+      ~                                                      |
+                                                             |
+    ]])
+  end)
+
+  it('<<< marker shows with tabline, winbar and splits', function()
+    screen:try_resize(40, 12)
+    exec([[
+      call setline(1, ['Line' .. (' with some text'->repeat(7))]->repeat(7))
+      set smoothscroll scrolloff=0
+      norm sj
+    ]])
+    screen:expect([[
+      <<<e text with some text with some text |
+      with some text with some text           |
+      Line with some text with some text with |
+      some text with some text with some text |
+      with some text with some text           |
+      [No Name] [+]                           |
+      <<<e text with some text with some text |
+      ^with some text with some text           |
+      Line with some text with some text with |
+      some text with some text with some te@@@|
+      [No Name] [+]                           |
+                                              |
+    ]])
+    exec('set showtabline=2')
+    feed('<C-E>')
+    screen:expect([[
+       2+ [No Name]                           |
+      <<<e text with some text with some text |
+      with some text with some text           |
+      Line with some text with some text with |
+      some text with some text with some text |
+      with some text with some text           |
+      [No Name] [+]                           |
+      <<<e text with some text with some text |
+      ^with some text with some text           |
+      Line with some text with some text wi@@@|
+      [No Name] [+]                           |
+                                              |
+    ]])
+    exec('set winbar=winbar')
+    feed('<C-w>k<C-E>')
+    screen:expect([[
+       2+ [No Name]                           |
+      winbar                                  |
+      <<<e text with some text with some text |
+      ^with some text with some text           |
+      Line with some text with some text with |
+      some text with some text with some te@@@|
+      [No Name] [+]                           |
+      winbar                                  |
+      <<<e text with some text with some text |
+      with some text with some text           |
+      [No Name] [+]                           |
+                                              |
+    ]])
+  end)
+end)
diff --git a/test/functional/ui/popupmenu_spec.lua b/test/functional/ui/popupmenu_spec.lua
index 0b71e12b6f..6c26c8ea39 100644
--- a/test/functional/ui/popupmenu_spec.lua
+++ b/test/functional/ui/popupmenu_spec.lua
@@ -2396,7 +2396,7 @@ describe('builtin popupmenu', function()
         -- can't draw the pum, but check we don't crash
         screen:try_resize(12,2)
         screen:expect([[
-          text^        |
+          {1:<<<}t^        |
           {2:-- INSERT -} |
         ]])
 
diff --git a/test/old/testdir/test_alot.vim b/test/old/testdir/test_alot.vim
index 4a22315b9f..2a959f0834 100644
--- a/test/old/testdir/test_alot.vim
+++ b/test/old/testdir/test_alot.vim
@@ -17,7 +17,6 @@ source test_global.vim
 source test_move.vim
 source test_put.vim
 source test_reltime.vim
-source test_scroll_opt.vim
 source test_searchpos.vim
 source test_set.vim
 source test_shift.vim
diff --git a/test/old/testdir/test_breakindent.vim b/test/old/testdir/test_breakindent.vim
index 0d1753182e..f6c0e32adf 100644
--- a/test/old/testdir/test_breakindent.vim
+++ b/test/old/testdir/test_breakindent.vim
@@ -87,7 +87,7 @@ func Test_breakindent02_vartabs()
   endif
   " simple breakindent test with showbreak set
   call s:test_windows('setl briopt=min:0 sbr=>> vts=4')
-  let lines = s:screen_lines(line('.'),8)
+  let lines = s:screen_lines(line('.'), 8)
   let expect = [
 	\ "    abcd",
 	\ "    >>qr",
@@ -100,7 +100,7 @@ endfunc
 func Test_breakindent03()
   " simple breakindent test with showbreak set and briopt including sbr
   call s:test_windows('setl briopt=sbr,min:0 sbr=++')
-  let lines = s:screen_lines(line('.'),8)
+  let lines = s:screen_lines(line('.'), 8)
   let expect=[
 \ "    abcd",
 \ "++  qrst",
@@ -117,7 +117,7 @@ func Test_breakindent03_vartabs()
     return
   endif
   call s:test_windows('setl briopt=sbr,min:0 sbr=++ vts=4')
-  let lines = s:screen_lines(line('.'),8)
+  let lines = s:screen_lines(line('.'), 8)
   let expect = [
 	\ "    abcd",
 	\ "++  qrst",
@@ -132,7 +132,7 @@ func Test_breakindent04()
   " breakindent set with min width 18
   set sbr=<<<
   call s:test_windows('setl sbr=NONE briopt=min:18')
-  let lines = s:screen_lines(line('.'),8)
+  let lines = s:screen_lines(line('.'), 8)
   let expect = [
 	\ "    abcd",
 	\ "  qrstuv",
@@ -150,7 +150,7 @@ func Test_breakindent04_vartabs()
     return
   endif
   call s:test_windows('setl sbr= briopt=min:18 vts=4')
-  let lines = s:screen_lines(line('.'),8)
+  let lines = s:screen_lines(line('.'), 8)
   let expect = [
 	\ "    abcd",
 	\ "  qrstuv",
@@ -583,7 +583,7 @@ func Test_breakindent16()
   redraw!
   let lines = s:screen_lines(1,10)
   let expect = [
-	\ "    789012",
+	\ "<<< 789012",
 	\ "    345678",
 	\ "    901234",
 	\ ]
@@ -611,7 +611,7 @@ func Test_breakindent16_vartabs()
   redraw!
   let lines = s:screen_lines(1,10)
   let expect = [
-	\ "    789012",
+	\ "<<< 789012",
 	\ "    345678",
 	\ "    901234",
 	\ ]
@@ -711,25 +711,25 @@ endfunc
 func Test_breakindent20_cpo_n_nextpage()
   let s:input = ""
   call s:test_windows('setl breakindent briopt=min:14 cpo+=n number')
-  call setline(1, repeat('a', 200))
+  call setline(1, repeat('abcdefghijklmnopqrst', 10))
   norm! 1gg
   redraw!
   let lines = s:screen_lines(1, 20)
   let expect = [
-	\ "  1 aaaaaaaaaaaaaaaa",
-	\ "    aaaaaaaaaaaaaaaa",
-	\ "    aaaaaaaaaaaaaaaa",
+	\ "  1 abcdefghijklmnop",
+	\ "    qrstabcdefghijkl",
+	\ "    mnopqrstabcdefgh",
 	\ ]
   call s:compare_lines(expect, lines)
   " Scroll down one screen line
   setl scrolloff=5
-  norm! 5gj
+  norm! 6gj
   redraw!
   let lines = s:screen_lines(1, 20)
   let expect = [
-	\ "--1 aaaaaaaaaaaaaaaa",
-	\ "    aaaaaaaaaaaaaaaa",
-	\ "    aaaaaaaaaaaaaaaa",
+	\ "<<< qrstabcdefghijkl",
+	\ "    mnopqrstabcdefgh",
+	\ "    ijklmnopqrstabcd",
 	\ ]
   call s:compare_lines(expect, lines)
 
@@ -737,18 +737,18 @@ func Test_breakindent20_cpo_n_nextpage()
   norm! 1gg
   let lines = s:screen_lines(1, 20)
   let expect = [
-	\ "  1 aaaaaaaaaaaaaaaa",
-	\ "      aaaaaaaaaaaaaa",
-	\ "      aaaaaaaaaaaaaa",
+	\ "  1 abcdefghijklmnop",
+	\ "      qrstabcdefghij",
+	\ "      klmnopqrstabcd",
 	\ ]
   call s:compare_lines(expect, lines)
   " Scroll down one screen line
-  norm! 5gj
+  norm! 6gj
   let lines = s:screen_lines(1, 20)
   let expect = [
-	\ "--1   aaaaaaaaaaaaaa",
-	\ "      aaaaaaaaaaaaaa",
-	\ "      aaaaaaaaaaaaaa",
+	\ "<<<   qrstabcdefghij",
+	\ "      klmnopqrstabcd",
+	\ "      efghijklmnopqr",
 	\ ]
   call s:compare_lines(expect, lines)
 
diff --git a/test/old/testdir/test_diffmode.vim b/test/old/testdir/test_diffmode.vim
index 0049398776..ac90aaaa02 100644
--- a/test/old/testdir/test_diffmode.vim
+++ b/test/old/testdir/test_diffmode.vim
@@ -1605,6 +1605,21 @@ func Test_diff_scroll()
   call delete('Xright')
 endfunc
 
+" This was scrolling too many lines.
+func Test_diff_scroll_wrap_on()
+  20new
+  40vsplit
+  call setline(1, map(range(1, 9), 'repeat(v:val, 200)'))
+  setlocal number diff so=0
+  redraw
+  normal! jj
+  call assert_equal(1, winsaveview().topline)
+  normal! j
+  call assert_equal(2, winsaveview().topline)
+  bwipe!
+  bwipe!
+endfunc
+
 " This was trying to update diffs for a buffer being closed
 func Test_diff_only()
   silent! lfile
diff --git a/test/old/testdir/test_display.vim b/test/old/testdir/test_display.vim
index b642f39c9f..f27a8362a9 100644
--- a/test/old/testdir/test_display.vim
+++ b/test/old/testdir/test_display.vim
@@ -478,5 +478,26 @@ func Test_display_lastline()
   call assert_fails(':set fillchars=lastline:〇', 'E474:')
 endfunc
 
+func Test_display_long_lastline()
+  CheckScreendump
+
+  let lines =<< trim END
+    set display=lastline
+    call setline(1, [
+      \'aaaaa'->repeat(100),
+      \'bbbbb '->repeat(7) .. 'ccccc '->repeat(7) .. 'ddddd '->repeat(7)
+    \])
+  END
+
+  call writefile(lines, 'XdispLongline', 'D')
+  let buf = RunVimInTerminal('-S XdispLongline', #{rows: 14, cols: 35})
+
+  call term_sendkeys(buf, "482|")
+  call VerifyScreenDump(buf, 'Test_display_long_line_1', {})
+  call term_sendkeys(buf, "D")
+  call VerifyScreenDump(buf, 'Test_display_long_line_2', {})
+
+  call StopVimInTerminal(buf)
+endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/test/old/testdir/test_listlbr.vim b/test/old/testdir/test_listlbr.vim
index a746779e73..2e66fd4ccb 100644
--- a/test/old/testdir/test_listlbr.vim
+++ b/test/old/testdir/test_listlbr.vim
@@ -223,7 +223,7 @@ func Test_virtual_block_and_vbA()
   exe "norm! $3B\<C-v>eAx\<Esc>"
   let lines = s:screen_lines([1, 10], winwidth(0))
   let expect = [
-\ "foobar foobar       ",
+\ "<<<bar foobar       ",
 \ "foobar foobar       ",
 \ "foobar foobar       ",
 \ "foobar foobar       ",
diff --git a/test/old/testdir/test_listlbr_utf8.vim b/test/old/testdir/test_listlbr_utf8.vim
index df1ed78119..15b248964f 100644
--- a/test/old/testdir/test_listlbr_utf8.vim
+++ b/test/old/testdir/test_listlbr_utf8.vim
@@ -266,7 +266,7 @@ func Test_chinese_char_on_wrap_column()
   norm! $
   redraw!
   let expect=[
-\ '中aaaaaaaaaaaaaaaaa>',
+\ '<<<aaaaaaaaaaaaaaaa>',
 \ '中aaaaaaaaaaaaaaaaa>',
 \ '中aaaaaaaaaaaaaaaaa>',
 \ '中aaaaaaaaaaaaaaaaa>',
diff --git a/test/old/testdir/test_normal.vim b/test/old/testdir/test_normal.vim
index fe8611d527..600e58848b 100644
--- a/test/old/testdir/test_normal.vim
+++ b/test/old/testdir/test_normal.vim
@@ -3738,15 +3738,45 @@ endfunc
 " Test for 'scrolloff' with a long line that doesn't fit in the screen
 func Test_normal_scroloff()
   10new
-  80vnew
-  call setline(1, repeat('a', 1000))
+  60vnew
+  call setline(1, ' 1 ' .. repeat('a', 57)
+             \ .. ' 2 ' .. repeat('b', 57)
+             \ .. ' 3 ' .. repeat('c', 57)
+             \ .. ' 4 ' .. repeat('d', 57)
+             \ .. ' 5 ' .. repeat('e', 57)
+             \ .. ' 6 ' .. repeat('f', 57)
+             \ .. ' 7 ' .. repeat('g', 57)
+             \ .. ' 8 ' .. repeat('h', 57)
+             \ .. ' 9 ' .. repeat('i', 57)
+             \ .. '10 ' .. repeat('j', 57)
+             \ .. '11 ' .. repeat('k', 57)
+             \ .. '12 ' .. repeat('l', 57)
+             \ .. '13 ' .. repeat('m', 57)
+             \ .. '14 ' .. repeat('n', 57)
+             \ .. '15 ' .. repeat('o', 57)
+             \ .. '16 ' .. repeat('p', 57)
+             \ .. '17 ' .. repeat('q', 57)
+             \ .. '18 ' .. repeat('r', 57)
+             \ .. '19 ' .. repeat('s', 57)
+             \ .. '20 ' .. repeat('t', 57)
+             \ .. '21 ' .. repeat('u', 57)
+             \ .. '22 ' .. repeat('v', 57)
+             \ .. '23 ' .. repeat('w', 57)
+             \ .. '24 ' .. repeat('x', 57)
+             \ .. '25 ' .. repeat('y', 57)
+             \ .. '26 ' .. repeat('z', 57)
+             \ )
   set scrolloff=10
   normal gg10gj
-  call assert_equal(8, winline())
+  call assert_equal(6, winline())
   normal 10gj
-  call assert_equal(10, winline())
+  call assert_equal(6, winline())
   normal 10gk
-  call assert_equal(3, winline())
+  call assert_equal(6, winline())
+  normal 0
+  call assert_equal(1, winline())
+  normal $
+  call assert_equal(10, winline())
   set scrolloff&
   close!
 endfunc
diff --git a/test/old/testdir/test_number.vim b/test/old/testdir/test_number.vim
index 521b0cf706..cf777fd918 100644
--- a/test/old/testdir/test_number.vim
+++ b/test/old/testdir/test_number.vim
@@ -138,7 +138,7 @@ func Test_number_with_linewrap1()
   call s:validate_cursor()
   let lines = s:screen_lines(1, 3)
   let expect = [
-\ "--1 aaaa",
+\ "<<< aaaa",
 \ "    aaaa",
 \ "    aaaa",
 \ ]
diff --git a/test/old/testdir/test_options.vim b/test/old/testdir/test_options.vim
index f101f550d1..8fc86a99e3 100644
--- a/test/old/testdir/test_options.vim
+++ b/test/old/testdir/test_options.vim
@@ -721,7 +721,7 @@ func Test_backupskip()
   let &backupskip = backupskip
 endfunc
 
-func Test_copy_winopt()
+func Test_buf_copy_winopt()
   set hidden
 
   " Test copy option from current buffer in window
@@ -775,6 +775,108 @@ func Test_copy_winopt()
   set hidden&
 endfunc
 
+func Test_split_copy_options()
+  let values = [
+    \['cursorbind', 1, 0],
+    \['fillchars', '"vert:-"', '"' .. &fillchars .. '"'],
+    \['list', 1, 0],
+    \['listchars', '"space:-"', '"' .. &listchars .. '"'],
+    \['number', 1, 0],
+    \['relativenumber', 1, 0],
+    \['scrollbind', 1, 0],
+    \['smoothscroll', 1, 0],
+    \['virtualedit', '"block"', '"' .. &virtualedit .. '"'],
+    "\ ['wincolor', '"Search"', '"' .. &wincolor .. '"'],
+    \['wrap', 0, 1],
+  \]
+  if has('linebreak')
+    let values += [
+      \['breakindent', 1, 0],
+      \['breakindentopt', '"min:5"', '"' .. &breakindentopt .. '"'],
+      \['linebreak', 1, 0],
+      \['numberwidth', 7, 4],
+      \['showbreak', '"++"', '"' .. &showbreak .. '"'],
+    \]
+  endif
+  if has('rightleft')
+    let values += [
+      \['rightleft', 1, 0],
+      \['rightleftcmd', '"search"', '"' .. &rightleftcmd .. '"'],
+    \]
+  endif
+  if has('statusline')
+    let values += [
+      \['statusline', '"---%f---"', '"' .. &statusline .. '"'],
+    \]
+  endif
+  if has('spell')
+    let values += [
+      \['spell', 1, 0],
+    \]
+  endif
+  if has('syntax')
+    let values += [
+      \['cursorcolumn', 1, 0],
+      \['cursorline', 1, 0],
+      \['cursorlineopt', '"screenline"', '"' .. &cursorlineopt .. '"'],
+      \['colorcolumn', '"+1"', '"' .. &colorcolumn .. '"'],
+    \]
+  endif
+  if has('diff')
+    let values += [
+      \['diff', 1, 0],
+    \]
+  endif
+  if has('conceal')
+    let values += [
+      \['concealcursor', '"nv"', '"' .. &concealcursor .. '"'],
+      \['conceallevel', '3', &conceallevel],
+    \]
+  endif
+  if has('terminal')
+    let values += [
+      \['termwinkey', '"<C-X>"', '"' .. &termwinkey .. '"'],
+      \['termwinsize', '"10x20"', '"' .. &termwinsize .. '"'],
+    \]
+  endif
+  if has('folding')
+    let values += [
+      \['foldcolumn', '"5"',  &foldcolumn],
+      \['foldenable', 0, 1],
+      \['foldexpr', '"2 + 3"', '"' .. &foldexpr .. '"'],
+      \['foldignore', '"+="', '"' .. &foldignore .. '"'],
+      \['foldlevel', 4,  &foldlevel],
+      \['foldmarker', '">>,<<"', '"' .. &foldmarker .. '"'],
+      \['foldmethod', '"marker"', '"' .. &foldmethod .. '"'],
+      \['foldminlines', 3,  &foldminlines],
+      \['foldnestmax', 17,  &foldnestmax],
+      \['foldtext', '"closed"', '"' .. &foldtext .. '"'],
+    \]
+  endif
+  if has('signs')
+    let values += [
+      \['signcolumn', '"number"', '"' .. &signcolumn .. '"'],
+    \]
+  endif
+
+  " set options to non-default value
+  for item in values
+    exe $"let &{item[0]} = {item[1]}"
+  endfor
+
+  " check values are set in new window
+  split
+  for item in values
+    exe $'call assert_equal({item[1]}, &{item[0]}, "{item[0]}")'
+  endfor
+
+  " restore
+  close
+  for item in values
+    exe $"let &{item[0]} = {item[1]}"
+  endfor
+endfunc
+
 func Test_shortmess_F()
   new
   call assert_match('\[No Name\]', execute('file'))
diff --git a/test/old/testdir/test_scroll_opt.vim b/test/old/testdir/test_scroll_opt.vim
index 64f4ced470..4ed54591af 100644
--- a/test/old/testdir/test_scroll_opt.vim
+++ b/test/old/testdir/test_scroll_opt.vim
@@ -1,4 +1,8 @@
-" Test for reset 'scroll'
+" Test for reset 'scroll' and 'smoothscroll'
+
+source check.vim
+source screendump.vim
+source mouse.vim
 
 func Test_reset_scroll()
   let scr = &l:scroll
@@ -51,4 +55,554 @@ func Test_scolloff_even_line_count()
    bwipe!
 endfunc
 
+func Test_CtrlE_CtrlY_stop_at_end()
+  enew
+  call setline(1, ['one', 'two'])
+  set number
+  exe "normal \<C-Y>"
+  call assert_equal(["  1 one   "], ScreenLines(1, 10))
+  exe "normal \<C-E>\<C-E>\<C-E>"
+  call assert_equal(["  2 two   "], ScreenLines(1, 10))
+
+  bwipe!
+  set nonumber
+endfunc
+
+func Test_smoothscroll_CtrlE_CtrlY()
+  CheckScreendump
+
+  let lines =<< trim END
+      vim9script
+      setline(1, [
+        'line one',
+        'word '->repeat(20),
+        'line three',
+        'long word '->repeat(7),
+        'line',
+        'line',
+        'line',
+      ])
+      set smoothscroll
+      :5
+  END
+  call writefile(lines, 'XSmoothScroll', 'D')
+  let buf = RunVimInTerminal('-S XSmoothScroll', #{rows: 12, cols: 40})
+
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smoothscroll_1', {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smoothscroll_2', {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smoothscroll_3', {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smoothscroll_4', {})
+
+  call term_sendkeys(buf, "\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smoothscroll_5', {})
+  call term_sendkeys(buf, "\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smoothscroll_6', {})
+  call term_sendkeys(buf, "\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smoothscroll_7', {})
+  call term_sendkeys(buf, "\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smoothscroll_8', {})
+
+  if has('folding')
+    call term_sendkeys(buf, ":set foldmethod=indent\<CR>")
+    " move the cursor so we can reuse the same dumps
+    call term_sendkeys(buf, "5G")
+    call term_sendkeys(buf, "\<C-E>")
+    call VerifyScreenDump(buf, 'Test_smoothscroll_1', {})
+    call term_sendkeys(buf, "\<C-E>")
+    call VerifyScreenDump(buf, 'Test_smoothscroll_2', {})
+    call term_sendkeys(buf, "7G")
+    call term_sendkeys(buf, "\<C-Y>")
+    call VerifyScreenDump(buf, 'Test_smoothscroll_7', {})
+    call term_sendkeys(buf, "\<C-Y>")
+    call VerifyScreenDump(buf, 'Test_smoothscroll_8', {})
+  endif
+
+  call StopVimInTerminal(buf)
+endfunc
+
+func Test_smoothscroll_number()
+  CheckScreendump
+
+  let lines =<< trim END
+      vim9script
+      setline(1, [
+        'one ' .. 'word '->repeat(20),
+        'two ' .. 'long word '->repeat(7),
+        'line',
+        'line',
+        'line',
+      ])
+      set smoothscroll
+      set number cpo+=n
+      :3
+
+      def g:DoRel()
+        set number relativenumber scrolloff=0
+        :%del
+        setline(1, [
+          'one',
+          'very long text '->repeat(12),
+          'three',
+        ])
+        exe "normal 2Gzt\<C-E>"
+      enddef
+  END
+  call writefile(lines, 'XSmoothNumber', 'D')
+  let buf = RunVimInTerminal('-S XSmoothNumber', #{rows: 12, cols: 40})
+
+  call VerifyScreenDump(buf, 'Test_smooth_number_1', {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smooth_number_2', {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smooth_number_3', {})
+
+  call term_sendkeys(buf, ":set cpo-=n\<CR>")
+  call VerifyScreenDump(buf, 'Test_smooth_number_4', {})
+  call term_sendkeys(buf, "\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smooth_number_5', {})
+  call term_sendkeys(buf, "\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smooth_number_6', {})
+
+  call term_sendkeys(buf, ":call DoRel()\<CR>")
+  call VerifyScreenDump(buf, 'Test_smooth_number_7', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
+func Test_smoothscroll_list()
+  CheckScreendump
+
+  let lines =<< trim END
+      vim9script
+      set smoothscroll scrolloff=0
+      set list
+      setline(1, [
+        'one',
+        'very long text '->repeat(12),
+        'three',
+      ])
+      exe "normal 2Gzt\<C-E>"
+  END
+  call writefile(lines, 'XSmoothList', 'D')
+  let buf = RunVimInTerminal('-S XSmoothList', #{rows: 8, cols: 40})
+
+  call VerifyScreenDump(buf, 'Test_smooth_list_1', {})
+
+  call term_sendkeys(buf, ":set listchars+=precedes:#\<CR>")
+  call VerifyScreenDump(buf, 'Test_smooth_list_2', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
+func Test_smoothscroll_diff_mode()
+  CheckScreendump
+
+  let lines =<< trim END
+      vim9script
+      var text = 'just some text here'
+      setline(1, text)
+      set smoothscroll
+      diffthis
+      new
+      setline(1, text)
+      set smoothscroll
+      diffthis
+  END
+  call writefile(lines, 'XSmoothDiff', 'D')
+  let buf = RunVimInTerminal('-S XSmoothDiff', #{rows: 8})
+
+  call VerifyScreenDump(buf, 'Test_smooth_diff_1', {})
+  call term_sendkeys(buf, "\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smooth_diff_1', {})
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smooth_diff_1', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
+func Test_smoothscroll_wrap_scrolloff_zero()
+  CheckScreendump
+
+  let lines =<< trim END
+      vim9script
+      setline(1, ['Line' .. (' with some text'->repeat(7))]->repeat(7))
+      set smoothscroll scrolloff=0
+      :3
+  END
+  call writefile(lines, 'XSmoothWrap', 'D')
+  let buf = RunVimInTerminal('-S XSmoothWrap', #{rows: 8, cols: 40})
+
+  call VerifyScreenDump(buf, 'Test_smooth_wrap_1', {})
+
+  " moving cursor down - whole bottom line shows
+  call term_sendkeys(buf, "j")
+  call VerifyScreenDump(buf, 'Test_smooth_wrap_2', {})
+
+  call term_sendkeys(buf, "\<C-E>j")
+  call VerifyScreenDump(buf, 'Test_smooth_wrap_3', {})
+
+  call term_sendkeys(buf, "G")
+  call VerifyScreenDump(buf, 'Test_smooth_wrap_4', {})
+
+  " moving cursor up right after the >>> marker - no need to show whole line
+  call term_sendkeys(buf, "2gj3l2k")
+  call VerifyScreenDump(buf, 'Test_smooth_wrap_5', {})
+
+  " moving cursor up where the >>> marker is - whole top line shows
+  call term_sendkeys(buf, "2j02k")
+  call VerifyScreenDump(buf, 'Test_smooth_wrap_6', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
+func Test_smoothscroll_wrap_long_line()
+  CheckScreendump
+
+  let lines =<< trim END
+      vim9script
+      setline(1, ['one', 'two', 'Line' .. (' with lots of text'->repeat(30)) .. ' end', 'four'])
+      set smoothscroll scrolloff=0
+      normal 3G10|zt
+  END
+  call writefile(lines, 'XSmoothWrap', 'D')
+  let buf = RunVimInTerminal('-S XSmoothWrap', #{rows: 6, cols: 40})
+  call VerifyScreenDump(buf, 'Test_smooth_long_1', {})
+
+  " scrolling up, cursor moves screen line down
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smooth_long_2', {})
+  call term_sendkeys(buf, "5\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smooth_long_3', {})
+
+  " scrolling down, cursor moves screen line up
+  call term_sendkeys(buf, "5\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smooth_long_4', {})
+  call term_sendkeys(buf, "\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smooth_long_5', {})
+
+  " 'scrolloff' set to 1, scrolling up, cursor moves screen line down
+  call term_sendkeys(buf, ":set scrolloff=1\<CR>")
+  call term_sendkeys(buf, "10|\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smooth_long_6', {})
+  
+  " 'scrolloff' set to 1, scrolling down, cursor moves screen line up
+  call term_sendkeys(buf, "\<C-E>")
+  call term_sendkeys(buf, "gjgj")
+  call term_sendkeys(buf, "\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smooth_long_7', {})
+  
+  " 'scrolloff' set to 2, scrolling up, cursor moves screen line down
+  call term_sendkeys(buf, ":set scrolloff=2\<CR>")
+  call term_sendkeys(buf, "10|\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smooth_long_8', {})
+  
+  " 'scrolloff' set to 2, scrolling down, cursor moves screen line up
+  call term_sendkeys(buf, "\<C-E>")
+  call term_sendkeys(buf, "gj")
+  call term_sendkeys(buf, "\<C-Y>")
+  call VerifyScreenDump(buf, 'Test_smooth_long_9', {})
+
+  " 'scrolloff' set to 0, move cursor down one line.
+  " Cursor should move properly, and since this is a really long line, it will
+  " be put on top of the screen.
+  call term_sendkeys(buf, ":set scrolloff=0\<CR>")
+  call term_sendkeys(buf, "0j")
+  call VerifyScreenDump(buf, 'Test_smooth_long_10', {})
+
+  " Test zt/zz/zb that they work properly when a long line is above it
+  call term_sendkeys(buf, "zb")
+  call VerifyScreenDump(buf, 'Test_smooth_long_11', {})
+  call term_sendkeys(buf, "zz")
+  call VerifyScreenDump(buf, 'Test_smooth_long_12', {})
+  call term_sendkeys(buf, "zt")
+  call VerifyScreenDump(buf, 'Test_smooth_long_13', {})
+
+  " Repeat the step and move the cursor down again.
+  " This time, use a shorter long line that is barely long enough to span more
+  " than one window. Note that the cursor is at the bottom this time because
+  " Vim prefers to do so if we are scrolling a few lines only.
+  call term_sendkeys(buf, ":call setline(1, ['one', 'two', 'Line' .. (' with lots of text'->repeat(10)) .. ' end', 'four'])\<CR>")
+  call term_sendkeys(buf, "3Gzt")
+  call term_sendkeys(buf, "j")
+  call VerifyScreenDump(buf, 'Test_smooth_long_14', {})
+
+  " Repeat the step but this time start it when the line is smooth-scrolled by
+  " one line. This tests that the offset calculation is still correct and
+  " still end up scrolling down to the next line with cursor at bottom of
+  " screen.
+  call term_sendkeys(buf, "3Gzt")
+  call term_sendkeys(buf, "\<C-E>j")
+  call VerifyScreenDump(buf, 'Test_smooth_long_15', {})
+  
+  call StopVimInTerminal(buf)
+endfunc
+
+func Test_smoothscroll_one_long_line()
+  CheckScreendump
+
+  let lines =<< trim END
+      vim9script
+      setline(1, 'with lots of text '->repeat(7))
+      set smoothscroll scrolloff=0
+  END
+  call writefile(lines, 'XSmoothOneLong', 'D')
+  let buf = RunVimInTerminal('-S XSmoothOneLong', #{rows: 6, cols: 40})
+  call VerifyScreenDump(buf, 'Test_smooth_one_long_1', {})
+  
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smooth_one_long_2', {})
+
+  call term_sendkeys(buf, "0")
+  call VerifyScreenDump(buf, 'Test_smooth_one_long_1', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
+func Test_smoothscroll_long_line_showbreak()
+  CheckScreendump
+
+  let lines =<< trim END
+      vim9script
+      # a line that spans four screen lines
+      setline(1, 'with lots of text in one line '->repeat(6))
+      set smoothscroll scrolloff=0 showbreak=+++\ 
+  END
+  call writefile(lines, 'XSmoothLongShowbreak', 'D')
+  let buf = RunVimInTerminal('-S XSmoothLongShowbreak', #{rows: 6, cols: 40})
+  call VerifyScreenDump(buf, 'Test_smooth_long_showbreak_1', {})
+  
+  call term_sendkeys(buf, "\<C-E>")
+  call VerifyScreenDump(buf, 'Test_smooth_long_showbreak_2', {})
+
+  call term_sendkeys(buf, "0")
+  call VerifyScreenDump(buf, 'Test_smooth_long_showbreak_1', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
+func s:check_col_calc(win_col, win_line, buf_col)
+  call assert_equal(a:win_col, wincol())
+  call assert_equal(a:win_line, winline())
+  call assert_equal(a:buf_col, col('.'))
+endfunc
+
+" Test that if the current cursor is on a smooth scrolled line, we correctly
+" reposition it. Also check that we don't miscalculate the values by checking
+" the consistency between wincol() and col('.') as they are calculated
+" separately in code.
+func Test_smoothscroll_cursor_position()
+  call NewWindow(10, 20)
+  setl smoothscroll wrap
+  call setline(1, "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
+
+  call s:check_col_calc(1, 1, 1)
+  exe "normal \<C-E>"
+
+  " Move down another line to avoid blocking the <<< display
+  call s:check_col_calc(1, 2, 41)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(1, 3, 41)
+
+  normal gg3l
+  exe "normal \<C-E>"
+
+  " Move down only 1 line when we are out of the range of the <<< display
+  call s:check_col_calc(4, 1, 24)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(4, 2, 24)
+  normal ggg$
+  exe "normal \<C-E>"
+  call s:check_col_calc(20, 1, 40)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(20, 2, 40)
+  normal gg
+
+  " Test number, where we have indented lines
+  setl number
+  call s:check_col_calc(5, 1, 1)
+  exe "normal \<C-E>"
+
+  " Move down only 1 line when the <<< display is on the number column
+  call s:check_col_calc(5, 1, 17)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(5, 2, 17)
+  normal ggg$
+  exe "normal \<C-E>"
+  call s:check_col_calc(20, 1, 32)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(20, 2, 32)
+  normal gg
+
+  setl numberwidth=1
+
+  " Move down another line when numberwidth is too short to cover the whole
+  " <<< display
+  call s:check_col_calc(3, 1, 1)
+  exe "normal \<C-E>"
+  call s:check_col_calc(3, 2, 37)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(3, 3, 37)
+  normal ggl
+
+  " Only move 1 line down when we are just past the <<< display
+  call s:check_col_calc(4, 1, 2)
+  exe "normal \<C-E>"
+  call s:check_col_calc(4, 1, 20)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(4, 2, 20)
+  normal gg
+  setl numberwidth&
+
+  " Test number + showbreak, so test that the additional indentation works
+  setl number showbreak=+++
+  call s:check_col_calc(5, 1, 1)
+  exe "normal \<C-E>"
+  call s:check_col_calc(8, 1, 17)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(8, 2, 17)
+  normal gg
+
+  " Test number + cpo+=n mode, where wrapped lines aren't indented
+  setl number cpo+=n showbreak=
+  call s:check_col_calc(5, 1, 1)
+  exe "normal \<C-E>"
+  call s:check_col_calc(1, 2, 37)
+  exe "normal \<C-Y>"
+  call s:check_col_calc(1, 3, 37)
+  normal gg
+
+  bwipe!
+endfunc
+
+func Test_smoothscroll_cursor_scrolloff()
+  call NewWindow(10, 20)
+  setl smoothscroll wrap
+  setl scrolloff=3
+  
+  " 120 chars are 6 screen lines
+  call setline(1, "abcdefghijklmnopqrstABCDEFGHIJKLMNOPQRSTabcdefghijklmnopqrstABCDEFGHIJKLMNOPQRSTabcdefghijklmnopqrstABCDEFGHIJKLMNOPQRST")
+  call setline(2, "below")
+
+  call s:check_col_calc(1, 1, 1)
+
+  " CTRL-E shows "<<<DEFG...", cursor move four lines down
+  exe "normal \<C-E>"
+  call s:check_col_calc(1, 4, 81)
+
+  " cursor on start of second line, "gk" moves into first line, skipcol doesn't
+  " change
+  exe "normal G0gk"
+  call s:check_col_calc(1, 5, 101)
+
+  " move cursor left one window width worth, scrolls one screen line
+  exe "normal 20h"
+  call s:check_col_calc(1, 5, 81)
+
+  " move cursor left one window width worth, scrolls one screen line
+  exe "normal 20h"
+  call s:check_col_calc(1, 4, 61)
+
+  " cursor on last line, "gk" should not cause a scroll
+  set scrolloff=0
+  normal G0
+  call s:check_col_calc(1, 7, 1)
+  normal gk
+  call s:check_col_calc(1, 6, 101)
+
+  bwipe!
+endfunc
+
+
+" Test that mouse picking is still accurate when we have smooth scrolled lines
+func Test_smoothscroll_mouse_pos()
+  CheckNotGui
+  CheckUnix
+
+  let save_mouse = &mouse
+  "let save_term = &term
+  "let save_ttymouse = &ttymouse
+  set mouse=a "term=xterm ttymouse=xterm2
+
+  call NewWindow(10, 20)
+  setl smoothscroll wrap
+  " First line will wrap to 3 physical lines. 2nd/3rd lines are short lines.
+  call setline(1, ["abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ", "line 2", "line 3"])
+
+  func s:check_mouse_click(row, col, buf_row, buf_col)
+    call MouseLeftClick(a:row, a:col)
+
+    call assert_equal(a:col, wincol())
+    call assert_equal(a:row, winline())
+    call assert_equal(a:buf_row, line('.'))
+    call assert_equal(a:buf_col, col('.'))
+  endfunc
+
+  " Check that clicking without scroll works first.
+  call s:check_mouse_click(3, 5, 1, 45)
+  call s:check_mouse_click(4, 1, 2, 1)
+  call s:check_mouse_click(4, 6, 2, 6)
+  call s:check_mouse_click(5, 1, 3, 1)
+  call s:check_mouse_click(5, 6, 3, 6)
+
+  " Smooth scroll, and checks that this didn't mess up mouse clicking
+  exe "normal \<C-E>"
+  call s:check_mouse_click(2, 5, 1, 45)
+  call s:check_mouse_click(3, 1, 2, 1)
+  call s:check_mouse_click(3, 6, 2, 6)
+  call s:check_mouse_click(4, 1, 3, 1)
+  call s:check_mouse_click(4, 6, 3, 6)
+
+  exe "normal \<C-E>"
+  call s:check_mouse_click(1, 5, 1, 45)
+  call s:check_mouse_click(2, 1, 2, 1)
+  call s:check_mouse_click(2, 6, 2, 6)
+  call s:check_mouse_click(3, 1, 3, 1)
+  call s:check_mouse_click(3, 6, 3, 6)
+
+  " Make a new first line 11 physical lines tall so it's taller than window
+  " height, to test overflow calculations with really long lines wrapping.
+  normal gg
+  call setline(1, "12345678901234567890"->repeat(11))
+  exe "normal 6\<C-E>"
+  call s:check_mouse_click(5, 1, 1, 201)
+  call s:check_mouse_click(6, 1, 2, 1)
+  call s:check_mouse_click(7, 1, 3, 1)
+
+  let &mouse = save_mouse
+  "let &term = save_term
+  "let &ttymouse = save_ttymouse
+endfunc
+
+" this was dividing by zero
+func Test_smoothscrol_zero_width()
+  CheckScreendump
+
+  let lines =<< trim END
+      winsize 0 0
+      vsplit
+      vsplit
+      vsplit
+      vsplit
+      vsplit
+      sil norm H
+      set wrap
+      set smoothscroll
+      set number
+  END
+  call writefile(lines, 'XSmoothScrollZero', 'D')
+  let buf = RunVimInTerminal('-u NONE -i NONE -n -m -X -Z -e -s -S XSmoothScrollZero', #{rows: 6, cols: 60, wait_for_ruler: 0})
+  call TermWait(buf, 3000)
+  call VerifyScreenDump(buf, 'Test_smoothscroll_zero_1', {})
+
+  call term_sendkeys(buf, ":sil norm \<C-V>\<C-W>\<C-V>\<C-N>\<CR>")
+  call VerifyScreenDump(buf, 'Test_smoothscroll_zero_2', {})
+
+  call StopVimInTerminal(buf)
+endfunc
+
+
 " vim: shiftwidth=2 sts=2 expandtab
diff --git a/test/old/testdir/test_window_cmd.vim b/test/old/testdir/test_window_cmd.vim
index f938203736..f18d1719c0 100644
--- a/test/old/testdir/test_window_cmd.vim
+++ b/test/old/testdir/test_window_cmd.vim
@@ -1734,7 +1734,7 @@ func Test_splitkeep_options()
   " let &t_WS = save_WS
 endfunc
 
-function Test_splitkeep_cmdwin_cursor_position()
+func Test_splitkeep_cmdwin_cursor_position()
   set splitkeep=screen
   call setline(1, range(&lines))
 
@@ -1759,9 +1759,9 @@ function Test_splitkeep_cmdwin_cursor_position()
 
   %bwipeout!
   set splitkeep&
-endfunction
+endfunc
 
-function Test_splitkeep_misc()
+func Test_splitkeep_misc()
   set splitkeep=screen
   set splitbelow
 
@@ -1794,7 +1794,7 @@ function Test_splitkeep_misc()
   set splitkeep&
 endfunc
 
-function Test_splitkeep_callback()
+func Test_splitkeep_callback()
   CheckScreendump
   let lines =<< trim END
     set splitkeep=screen
@@ -1827,7 +1827,7 @@ function Test_splitkeep_callback()
   call StopVimInTerminal(buf)
 endfunc
 
-function Test_splitkeep_fold()
+func Test_splitkeep_fold()
   CheckScreendump
 
   let lines =<< trim END
@@ -1857,9 +1857,9 @@ function Test_splitkeep_fold()
   call VerifyScreenDump(buf, 'Test_splitkeep_fold_4', {})
 
   call StopVimInTerminal(buf)
-endfunction
+endfunc
 
-function Test_splitkeep_status()
+func Test_splitkeep_status()
   CheckScreendump
 
   let lines =<< trim END
@@ -1877,9 +1877,9 @@ function Test_splitkeep_status()
   call VerifyScreenDump(buf, 'Test_splitkeep_status_1', {})
 
   call StopVimInTerminal(buf)
-endfunction
+endfunc
 
-function Test_new_help_window_on_error()
+func Test_new_help_window_on_error()
   help change.txt
   execute "normal! /CTRL-@\<CR>"
   silent! execute "normal! \<C-W>]"
@@ -1889,7 +1889,26 @@ function Test_new_help_window_on_error()
 
   call assert_equal(wincount, winnr('$'))
   call assert_equal(expand("<cword>"), "'mod'")
-endfunction
+endfunc
+
+func Test_smoothscroll_in_zero_width_window()
+  let save_lines = &lines
+  let save_columns = &columns
+
+  winsize 0 24
+  set cpo+=n
+  exe "noremap 0 \<C-W>n\<C-W>L"
+  norm 000000
+  set number smoothscroll
+  exe "norm \<C-Y>"
+
+  only!
+  let &lines = save_lines
+  let &columns = save_columns
+  set cpo-=n
+  unmap 0
+  set nonumber nosmoothscroll
+endfunc
 
 
 " vim: shiftwidth=2 sts=2 expandtab