msg: do not scroll entire screen (#8088)

27 files changed, 247 insertions, 86 deletions

diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index f4bf49c7c5..d9ce668962 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -2036,6 +2036,11 @@ A jump table for the options with a short description can be found at |Q_op|.
 			column of the last screen line.  Overrules "lastline".
 	uhex		Show unprintable characters hexadecimal as <xx>
 			instead of using ^C and ~C.
+	msgsep		When showing messages longer than 'cmdheight' lines,
+			only scroll the message lines and not the entire
+			screen. This also shows a separator line filled with
+			chars determined by 'fillchars' option, and
+			highlighted with the |MsgSeparator| group.
 
 	When neither "lastline" nor "truncate" is included, a last line that
 	doesn't fit is replaced with "@" lines.
@@ -2390,6 +2395,7 @@ A jump table for the options with a short description can be found at |Q_op|.
 	  vert:c	'│' or '|'	vertical separators |:vsplit|
 	  fold:c	'·' or '-'	filling 'foldtext'
 	  diff:c	'-'		deleted lines of the 'diff' option
+	  msgsep:c	' '		message separator 'display'
 
 	Any one that is omitted will fall back to the default.  For "stl" and
 	"stlnc" the space will be used when there is highlighting, '^' or '='
diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index ff9773b136..fa66d9d071 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -4909,6 +4909,8 @@ MatchParen	The character under the cursor or just before it, if it
 
 							*hl-ModeMsg*
 ModeMsg		'showmode' message (e.g., "-- INSERT --")
+							*hl-MsgSeparator*
+MsgSeparator	Separator for scrolled messages, `msgsep` flag of 'display'
 							*hl-MoreMsg*
 MoreMsg		|more-prompt|
 							*hl-NonText*
diff --git a/runtime/doc/vim_diff.txt b/runtime/doc/vim_diff.txt
index 3924dd4ebe..3575a420b7 100644
--- a/runtime/doc/vim_diff.txt
+++ b/runtime/doc/vim_diff.txt
@@ -34,7 +34,7 @@ a complete and centralized reference of those differences.
 - 'complete' doesn't include "i"
 - 'cscopeverbose' is enabled
 - 'directory' defaults to ~/.local/share/nvim/swap// (|xdg|), auto-created
-- 'display' defaults to "lastline"
+- 'display' defaults to "lastline,msgsep"
 - 'fillchars' defaults (in effect) to "vert:│,fold:·"
 - 'formatoptions' defaults to "tcqj"
 - 'history' defaults to 10000 (the maximum)
@@ -130,7 +130,9 @@ Some `CTRL-SHIFT-...` key chords are distinguished from `CTRL-...` variants
 
 Options:
   'cpoptions' flags: |cpo-_|
+  'display' flag `msgsep` to minimize scrolling when showing messages
   'guicursor' works in the terminal
+  'fillchars' flag `msgsep` (see 'display' above)
   'inccommand' shows interactive results for |:substitute|-like commands
   'scrollback'
   'statusline' supports unlimited alignment sections
@@ -164,6 +166,7 @@ Events:
 
 Highlight groups:
   |hl-NormalNC| highlights non-current windows
+  |hl-MsgSeparator| highlights separator for scrolled messages
   |hl-QuickFixLine|
   |hl-Substitute|
   |hl-TermCursor|
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 31bde4aa1e..776f131437 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -947,6 +947,7 @@ EXTERN int fill_stlnc INIT(= ' ');
 EXTERN int fill_vert INIT(= 9474);  // │
 EXTERN int fill_fold INIT(= 183);   // ·
 EXTERN int fill_diff INIT(= '-');
+EXTERN int fill_msgsep INIT(= ' ');
 
 /* Whether 'keymodel' contains "stopsel" and "startsel". */
 EXTERN int km_stopsel INIT(= FALSE);
diff --git a/src/nvim/highlight_defs.h b/src/nvim/highlight_defs.h
index 08157935f5..3518c8bdcc 100644
--- a/src/nvim/highlight_defs.h
+++ b/src/nvim/highlight_defs.h
@@ -87,6 +87,7 @@ typedef enum {
   , HLF_QFL         // selected quickfix line
   , HLF_0           // Whitespace
   , HLF_INACTIVE    // NormalNC: Normal text in non-current windows
+  , HLF_MSGSEP      // message separator line
   , HLF_COUNT       // MUST be the last one
 } hlf_T;
 
@@ -137,7 +138,8 @@ EXTERN const char *hlf_names[] INIT(= {
   [HLF_MC] = "ColorColumn",
   [HLF_QFL] = "QuickFixLine",
   [HLF_0] = "Whitespace",
-  [HLF_INACTIVE] = "NormalNC"
+  [HLF_INACTIVE] = "NormalNC",
+  [HLF_MSGSEP] = "MsgSeparator",
 });
 
 
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 12e5b844be..04528629c7 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -1875,13 +1875,29 @@ bool message_filtered(char_u *msg)
   return cmdmod.filter_force ? match : !match;
 }
 
+/// including horizontal separator
+int msg_scrollsize(void)
+{
+  return msg_scrolled + p_ch + 1;
+}
+
 /*
  * Scroll the screen up one line for displaying the next message line.
  */
 static void msg_scroll_up(void)
 {
-  /* scrolling up always works */
-  screen_del_lines(0, 0, 1, (int)Rows, NULL);
+  if (dy_flags & DY_MSGSEP) {
+    if (msg_scrolled == 0) {
+      screen_fill(Rows-p_ch-1, Rows-p_ch, 0, (int)Columns,
+                  fill_msgsep, fill_msgsep, hl_attr(HLF_MSGSEP));
+    }
+    int nscroll = MIN(msg_scrollsize()+1, Rows);
+    ui_call_set_scroll_region(Rows-nscroll, Rows-1, 0, Columns-1);
+    screen_del_lines(Rows-nscroll, 0, 1, nscroll, NULL);
+    ui_reset_scroll_region();
+  } else {
+    screen_del_lines(0, 0, 1, (int)Rows, NULL);
+  }
 }
 
 /*
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 41cfdf9856..c43ba2fc4f 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -3411,6 +3411,7 @@ static char_u *set_chars_option(char_u **varp)
     { &fill_vert,    "vert" , 9474 },  // │
     { &fill_fold,    "fold" , 183  },  // ·
     { &fill_diff,    "diff" , '-'  },
+    { &fill_msgsep,  "msgsep", ' ' },
   };
   static struct charstab lcstab[] = {
     { &lcs_eol,      "eol",      NUL },
diff --git a/src/nvim/option_defs.h b/src/nvim/option_defs.h
index e2e98f251e..66a49fd6e0 100644
--- a/src/nvim/option_defs.h
+++ b/src/nvim/option_defs.h
@@ -394,11 +394,13 @@ EXTERN char_u   *p_dir;         /* 'directory' */
 EXTERN char_u   *p_dy;          /* 'display' */
 EXTERN unsigned dy_flags;
 #ifdef IN_OPTION_C
-static char *(p_dy_values[]) = { "lastline", "truncate", "uhex", NULL };
+static char *(p_dy_values[]) = { "lastline", "truncate", "uhex", "msgsep",
+                                  NULL };
 #endif
 #define DY_LASTLINE             0x001
 #define DY_TRUNCATE             0x002
 #define DY_UHEX                 0x004
+#define DY_MSGSEP               0x008
 EXTERN int p_ed;                // 'edcompatible'
 EXTERN int p_emoji;             // 'emoji'
 EXTERN char_u   *p_ead;         // 'eadirection'
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index d653147943..80484d0ad2 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -642,7 +642,7 @@ return {
       vim=true,
       redraw={'all_windows'},
       varname='p_dy',
-      defaults={if_true={vi="", vim="lastline"}}
+      defaults={if_true={vi="", vim="lastline,msgsep"}}
     },
     {
       full_name='eadirection', abbreviation='ead',
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 22de08041a..05ad126fa0 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -300,13 +300,25 @@ void update_screen(int type)
    * if the screen was scrolled up when displaying a message, scroll it down
    */
   if (msg_scrolled) {
-    clear_cmdline = TRUE;
-    if (msg_scrolled > Rows - 5)            /* clearing is faster */
+    clear_cmdline = true;
+    if (dy_flags & DY_MSGSEP) {
+      FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
+        int valid = Rows - msg_scrollsize();
+        if (wp->w_winrow + wp->w_height > valid) {
+          wp->w_redr_type = NOT_VALID;
+          wp->w_lines_valid = 0;
+        }
+        if (wp->w_winrow + wp->w_height + wp->w_status_height > valid) {
+          wp->w_redr_status = true;
+        }
+      }
+    } else if (msg_scrolled > Rows - 5) {  // clearing is faster
       type = CLEAR;
-    else if (type != CLEAR) {
-      check_for_delay(FALSE);
-      if (screen_ins_lines(0, 0, msg_scrolled, (int)Rows, NULL) == FAIL)
+    } else if (type != CLEAR) {
+      check_for_delay(false);
+      if (screen_ins_lines(0, 0, msg_scrolled, (int)Rows, NULL) == FAIL) {
         type = CLEAR;
+      }
       FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
         if (wp->w_winrow < msg_scrolled) {
           if (wp->w_winrow + wp->w_height > msg_scrolled
diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index 8ec393e568..2613c09c19 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -5999,6 +5999,7 @@ static const char *highlight_init_both[] = {
   "default link QuickFixLine Search",
   "default link Substitute Search",
   "default link Whitespace NonText",
+  "default link MsgSeparator StatusLine",
   NULL
 };
 
diff --git a/test/functional/api/vim_spec.lua b/test/functional/api/vim_spec.lua
index bd56161a54..7ac20a99af 100644
--- a/test/functional/api/vim_spec.lua
+++ b/test/functional/api/vim_spec.lua
@@ -579,7 +579,8 @@ describe('api', function()
       screen:set_default_attr_ids({
         [0] = {bold=true, foreground=Screen.colors.Blue},
         [1] = {foreground = Screen.colors.White, background = Screen.colors.Red},
-        [2] = {bold = true, foreground = Screen.colors.SeaGreen}
+        [2] = {bold = true, foreground = Screen.colors.SeaGreen},
+        [3] = {bold = true, reverse = true},
       })
     end)
 
@@ -600,11 +601,11 @@ describe('api', function()
     it('shows return prompt when more than &cmdheight lines', function()
       nvim_async('err_write', 'something happened\nvery bad\n')
       screen:expect([[
+                                                |
         {0:~                                       }|
         {0:~                                       }|
         {0:~                                       }|
-        {0:~                                       }|
-        {0:~                                       }|
+        {3:                                        }|
         {1:something happened}                      |
         {1:very bad}                                |
         {2:Press ENTER or type command to continue}^ |
@@ -614,9 +615,9 @@ describe('api', function()
     it('shows return prompt after all lines are shown', function()
       nvim_async('err_write', 'FAILURE\nERROR\nEXCEPTION\nTRACEBACK\n')
       screen:expect([[
+                                                |
         {0:~                                       }|
-        {0:~                                       }|
-        {0:~                                       }|
+        {3:                                        }|
         {1:FAILURE}                                 |
         {1:ERROR}                                   |
         {1:EXCEPTION}                               |
@@ -644,11 +645,11 @@ describe('api', function()
       -- shows up to &cmdheight lines
       nvim_async('err_write', 'more fail\ntoo fail\n')
       screen:expect([[
+                                                |
         {0:~                                       }|
         {0:~                                       }|
         {0:~                                       }|
-        {0:~                                       }|
-        {0:~                                       }|
+        {3:                                        }|
         {1:more fail}                               |
         {1:too fail}                                |
         {2:Press ENTER or type command to continue}^ |
diff --git a/test/functional/autocmd/cmdline_spec.lua b/test/functional/autocmd/cmdline_spec.lua
index 8ea086fb46..3f0504d02f 100644
--- a/test/functional/autocmd/cmdline_spec.lua
+++ b/test/functional/autocmd/cmdline_spec.lua
@@ -59,24 +59,25 @@ describe('cmdline autocommands', function()
       [1] = {bold = true, foreground = Screen.colors.Blue1},
       [2] = {foreground = Screen.colors.Grey100, background = Screen.colors.Red},
       [3] = {bold = true, foreground = Screen.colors.SeaGreen4},
+      [4] = {bold = true, reverse = true},
     })
     command("autocmd CmdlineEnter * echoerr 'FAIL'")
     command("autocmd CmdlineLeave * echoerr 'very error'")
     feed(':')
     screen:expect([[
+                                                                              |
       {1:~                                                                       }|
       {1:~                                                                       }|
       {1:~                                                                       }|
-      {1:~                                                                       }|
-      {1:~                                                                       }|
+      {4:                                                                        }|
       :                                                                       |
       {2:E5500: autocmd has thrown an exception: Vim(echoerr):FAIL}               |
       :^                                                                       |
     ]])
     feed("put ='lorem ipsum'<cr>")
     screen:expect([[
-      {1:~                                                                       }|
-      {1:~                                                                       }|
+                                                                              |
+      {4:                                                                        }|
       :                                                                       |
       {2:E5500: autocmd has thrown an exception: Vim(echoerr):FAIL}               |
       :put ='lorem ipsum'                                                     |
diff --git a/test/functional/clipboard/clipboard_provider_spec.lua b/test/functional/clipboard/clipboard_provider_spec.lua
index a3ea3b568f..a40c080a6d 100644
--- a/test/functional/clipboard/clipboard_provider_spec.lua
+++ b/test/functional/clipboard/clipboard_provider_spec.lua
@@ -83,7 +83,14 @@ local function basic_register_test(noblock)
 end
 
 describe('clipboard', function()
-  before_each(clear)
+  local screen
+
+  before_each(function()
+    clear()
+    screen = Screen.new(72, 4)
+    screen:attach()
+    command("set display-=msgsep")
+  end)
 
   it('unnamed register works without provider', function()
     eq('"', eval('v:register'))
@@ -92,8 +99,6 @@ describe('clipboard', function()
 
   it('`:redir @+>` with invalid g:clipboard shows exactly one error #7184',
   function()
-    local screen = Screen.new(72, 4)
-    screen:attach()
     command("let g:clipboard = 'bogus'")
     feed_command('redir @+> | :silent echo system("cat CONTRIBUTING.md") | redir END')
     screen:expect([[
@@ -106,8 +111,6 @@ describe('clipboard', function()
 
   it('`:redir @+>|bogus_cmd|redir END` + invalid g:clipboard must not recurse #7184',
   function()
-    local screen = Screen.new(72, 4)
-    screen:attach()
     command("let g:clipboard = 'bogus'")
     feed_command('redir @+> | bogus_cmd | redir END')
     screen:expect([[
@@ -123,8 +126,6 @@ describe('clipboard', function()
     eq('', eval('provider#clipboard#Executable()'))
     eq('clipboard: invalid g:clipboard', eval('provider#clipboard#Error()'))
 
-    local screen = Screen.new(72, 4)
-    screen:attach()
     command("let g:clipboard = 'bogus'")
     -- Explicit clipboard attempt, should show a hint message.
     feed_command('let @+="foo"')
@@ -493,10 +494,10 @@ describe('clipboard', function()
     feed_command("let g:test_clip['+'] = ['such', 'plus', 'stuff']")
     feed_command("registers")
     screen:expect([[
-      ~                                                           |
-      ~                                                           |
-      ~                                                           |
-      ~                                                           |
+                                                                  |
+      {0:~                                                           }|
+      {0:~                                                           }|
+      {4:                                                            }|
       :registers                                                  |
       {1:--- Registers ---}                                           |
       "*   some{2:^J}star data{2:^J}                                      |
@@ -504,10 +505,11 @@ describe('clipboard', function()
       ":   let g:test_clip['+'] = ['such', 'plus', 'stuff']       |
       {3:Press ENTER or type command to continue}^                     |
     ]], {
+      [0] = {bold = true, foreground = Screen.colors.Blue},
       [1] = {bold = true, foreground = Screen.colors.Fuchsia},
       [2] = {foreground = Screen.colors.Blue},
-      [3] = {bold = true, foreground = Screen.colors.SeaGreen}},
-      {{bold = true, foreground = Screen.colors.Blue}})
+      [3] = {bold = true, foreground = Screen.colors.SeaGreen},
+      [4] = {bold = true, reverse = true}})
     feed('<cr>') -- clear out of Press ENTER screen
   end)
 
diff --git a/test/functional/eval/execute_spec.lua b/test/functional/eval/execute_spec.lua
index 183884a51e..925e311c7d 100644
--- a/test/functional/eval/execute_spec.lua
+++ b/test/functional/eval/execute_spec.lua
@@ -106,16 +106,22 @@ describe('execute()', function()
   end)
 
   it('does not corrupt the command display #5422', function()
-    local screen = Screen.new(70, 5)
+    local screen = Screen.new(70, 7)
     screen:attach()
     feed(':echo execute("hi ErrorMsg")<CR>')
     screen:expect([[
-      ~                                                                     |
-      ~                                                                     |
+                                                                            |
+      {1:~                                                                     }|
+      {1:~                                                                     }|
+      {2:                                                                      }|
       :echo execute("hi ErrorMsg")                                          |
       ErrorMsg       xxx ctermfg=15 ctermbg=1 guifg=White guibg=Red         |
-      Press ENTER or type command to continue^                               |
-    ]])
+      {3:Press ENTER or type command to continue}^                               |
+    ]], {
+      [1] = {bold = true, foreground = Screen.colors.Blue1},
+      [2] = {bold = true, reverse = true},
+      [3] = {bold = true, foreground = Screen.colors.SeaGreen4},
+    })
     feed('<CR>')
   end)
 
diff --git a/test/functional/eval/input_spec.lua b/test/functional/eval/input_spec.lua
index 1e6b107c60..777f49462d 100644
--- a/test/functional/eval/input_spec.lua
+++ b/test/functional/eval/input_spec.lua
@@ -58,6 +58,7 @@ before_each(function()
     RBP2={background=Screen.colors.Yellow},
     RBP3={background=Screen.colors.Green},
     RBP4={background=Screen.colors.Blue},
+    SEP={bold = true, reverse = true},
   })
 end)
 
@@ -65,9 +66,9 @@ describe('input()', function()
   it('works with multiline prompts', function()
     feed([[:call input("Test\nFoo")<CR>]])
     screen:expect([[
+                               |
       {EOB:~                        }|
-      {EOB:~                        }|
-      {EOB:~                        }|
+      {SEP:                         }|
       Test                     |
       Foo^                      |
     ]])
@@ -75,9 +76,9 @@ describe('input()', function()
   it('works with multiline prompts and :echohl', function()
     feed([[:echohl Test | call input("Test\nFoo")<CR>]])
     screen:expect([[
+                               |
       {EOB:~                        }|
-      {EOB:~                        }|
-      {EOB:~                        }|
+      {SEP:                         }|
       {T:Test}                     |
       {T:Foo}^                      |
     ]])
@@ -242,17 +243,17 @@ describe('input()', function()
   it('is not hidden by :silent', function()
     feed([[:silent call input('Foo: ')<CR>]])
     screen:expect([[
+                               |
       {EOB:~                        }|
-      {EOB:~                        }|
-      {EOB:~                        }|
+      {SEP:                         }|
       Foo: ^                    |
                                |
     ]])
     feed('Bar')
     screen:expect([[
+                               |
       {EOB:~                        }|
-      {EOB:~                        }|
-      {EOB:~                        }|
+      {SEP:                         }|
       Foo: Bar^                 |
                                |
     ]])
@@ -263,9 +264,9 @@ describe('inputdialog()', function()
   it('works with multiline prompts', function()
     feed([[:call inputdialog("Test\nFoo")<CR>]])
     screen:expect([[
+                               |
       {EOB:~                        }|
-      {EOB:~                        }|
-      {EOB:~                        }|
+      {SEP:                         }|
       Test                     |
       Foo^                      |
     ]])
@@ -273,9 +274,9 @@ describe('inputdialog()', function()
   it('works with multiline prompts and :echohl', function()
     feed([[:echohl Test | call inputdialog("Test\nFoo")<CR>]])
     screen:expect([[
+                               |
       {EOB:~                        }|
-      {EOB:~                        }|
-      {EOB:~                        }|
+      {SEP:                         }|
       {T:Test}                     |
       {T:Foo}^                      |
     ]])
diff --git a/test/functional/ex_cmds/cmd_map_spec.lua b/test/functional/ex_cmds/cmd_map_spec.lua
index 5b7f0942b1..77d025dcc7 100644
--- a/test/functional/ex_cmds/cmd_map_spec.lua
+++ b/test/functional/ex_cmds/cmd_map_spec.lua
@@ -27,6 +27,7 @@ describe('mappings with <Cmd>', function()
       [4] = {bold = true},
       [5] = {background = Screen.colors.LightGrey},
       [6] = {foreground = Screen.colors.Blue1},
+      [7] = {bold = true, reverse = true},
     })
     screen:attach()
 
@@ -342,11 +343,11 @@ describe('mappings with <Cmd>', function()
     -- error doesn't interrupt visual mode
     feed('ggvw<F6>')
     screen:expect([[
+      {5:some }short lines                                                 |
+      of test text                                                     |
       {1:~                                                                }|
       {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
+      {7:                                                                 }|
       {2:Error detected while processing :}                                |
       {2:E605: Exception not caught: very error}                           |
       {3:Press ENTER or type command to continue}^                          |
@@ -425,11 +426,11 @@ describe('mappings with <Cmd>', function()
     -- error doesn't interrupt temporary visual mode
     feed('<esc>ggvw<c-g><F6>')
     screen:expect([[
+      {5:some }short lines                                                 |
+      of test text                                                     |
       {1:~                                                                }|
       {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
+      {7:                                                                 }|
       {2:Error detected while processing :}                                |
       {2:E605: Exception not caught: very error}                           |
       {3:Press ENTER or type command to continue}^                          |
@@ -453,11 +454,11 @@ describe('mappings with <Cmd>', function()
     -- error doesn't interrupt select mode
     feed('<esc>ggvw<c-g><F1>')
     screen:expect([[
+      {5:some }short lines                                                 |
+      of test text                                                     |
       {1:~                                                                }|
       {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
+      {7:                                                                 }|
       {2:Error detected while processing :}                                |
       {2:E605: Exception not caught: very error}                           |
       {3:Press ENTER or type command to continue}^                          |
@@ -527,11 +528,11 @@ describe('mappings with <Cmd>', function()
     -- error aborts operator-pending, operator not performed
     feed('d<F6>')
     screen:expect([[
+      some short lines                                                 |
+      of test text                                                     |
       {1:~                                                                }|
       {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
+      {7:                                                                 }|
       {2:Error detected while processing :}                                |
       {2:E605: Exception not caught: very error}                           |
       {3:Press ENTER or type command to continue}^                          |
@@ -571,11 +572,11 @@ describe('mappings with <Cmd>', function()
 
     feed('<F6>')
     screen:expect([[
+      indeed some short little lines                                   |
+      of test text                                                     |
       {1:~                                                                }|
       {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
+      {7:                                                                 }|
       {2:Error detected while processing :}                                |
       {2:E605: Exception not caught: very error}                           |
       {3:Press ENTER or type command to continue}^                          |
@@ -675,10 +676,10 @@ describe('mappings with <Cmd>', function()
 
     feed(':echo 2<F6>')
     screen:expect([[
+      some short lines                                                 |
+      of test text                                                     |
       {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
+      {7:                                                                 }|
       :echo 2                                                          |
       {2:Error detected while processing :}                                |
       {2:E605: Exception not caught: very error}                           |
@@ -689,9 +690,9 @@ describe('mappings with <Cmd>', function()
     eq('c', eval('mode(1)'))
     feed('+2<cr>')
     screen:expect([[
-      {1:~                                                                }|
-      {1:~                                                                }|
-      {1:~                                                                }|
+      some short lines                                                 |
+      of test text                                                     |
+      {7:                                                                 }|
       :echo 2                                                          |
       {2:Error detected while processing :}                                |
       {2:E605: Exception not caught: very error}                           |
diff --git a/test/functional/ex_cmds/oldfiles_spec.lua b/test/functional/ex_cmds/oldfiles_spec.lua
index 4002855c24..448326cdfb 100644
--- a/test/functional/ex_cmds/oldfiles_spec.lua
+++ b/test/functional/ex_cmds/oldfiles_spec.lua
@@ -29,6 +29,7 @@ describe(':oldfiles', function()
   it('shows most recently used files', function()
     local screen = Screen.new(100, 5)
     screen:attach()
+    feed_command("set display-=msgsep")
     feed_command('edit testfile1')
     feed_command('edit testfile2')
     feed_command('wshada')
diff --git a/test/functional/lua/overrides_spec.lua b/test/functional/lua/overrides_spec.lua
index 8ca5fe57ba..007d40874f 100644
--- a/test/functional/lua/overrides_spec.lua
+++ b/test/functional/lua/overrides_spec.lua
@@ -87,6 +87,7 @@ describe('debug.debug', function()
       E = {foreground = Screen.colors.Grey100, background = Screen.colors.Red},
       cr = {bold = true, foreground = Screen.colors.SeaGreen4},
     })
+    command("set display-=msgsep")
   end)
   it('works', function()
     command([[lua
diff --git a/test/functional/ui/cmdline_highlight_spec.lua b/test/functional/ui/cmdline_highlight_spec.lua
index f9cec903a0..3c316d1cfa 100644
--- a/test/functional/ui/cmdline_highlight_spec.lua
+++ b/test/functional/ui/cmdline_highlight_spec.lua
@@ -24,6 +24,7 @@ before_each(function()
   clear()
   screen = Screen.new(40, 8)
   screen:attach()
+  command("set display-=msgsep")
   source([[
     highlight RBP1 guibg=Red
     highlight RBP2 guibg=Yellow
diff --git a/test/functional/ui/cursor_spec.lua b/test/functional/ui/cursor_spec.lua
index b47210a777..812c095add 100644
--- a/test/functional/ui/cursor_spec.lua
+++ b/test/functional/ui/cursor_spec.lua
@@ -194,8 +194,8 @@ describe('ui/cursor', function()
         if m.blinkoff then m.blinkoff = 400 end
         if m.blinkwait then m.blinkwait = 700 end
       end
-      if m.hl_id then m.hl_id = 48 end
-      if m.id_lm then m.id_lm = 49 end
+      if m.hl_id then m.hl_id = 49 end
+      if m.id_lm then m.id_lm = 50 end
     end
 
     -- Assert the new expectation.
diff --git a/test/functional/ui/highlight_spec.lua b/test/functional/ui/highlight_spec.lua
index e874c45272..364e0eea7f 100644
--- a/test/functional/ui/highlight_spec.lua
+++ b/test/functional/ui/highlight_spec.lua
@@ -94,6 +94,7 @@ describe('highlight defaults', function()
     clear()
     screen = Screen.new()
     screen:attach()
+    command("set display-=msgsep")
   end)
 
   after_each(function()
@@ -674,6 +675,76 @@ describe("'listchars' highlight", function()
   end)
 end)
 
+describe("MsgSeparator highlight and msgsep fillchar", function()
+  before_each(clear)
+  it("works", function()
+    local screen = Screen.new(50,5)
+    screen:set_default_attr_ids({
+      [1] = {bold=true, foreground=Screen.colors.Blue},
+      [2] = {bold=true, reverse=true},
+      [3] = {bold = true, foreground = Screen.colors.SeaGreen4},
+      [4] = {background = Screen.colors.Cyan, bold = true, reverse = true},
+      [5] = {bold = true, background = Screen.colors.Magenta}
+    })
+    screen:attach()
+
+    -- defaults
+    feed_command("ls")
+    screen:expect([[
+                                                        |
+      {2:                                                  }|
+      :ls                                               |
+        1 %a   "[No Name]"                    line 1    |
+      {3:Press ENTER or type command to continue}^           |
+    ]])
+    feed('<cr>')
+
+    feed_command("set fillchars+=msgsep:-")
+    feed_command("ls")
+    screen:expect([[
+                                                        |
+      {2:--------------------------------------------------}|
+      :ls                                               |
+        1 %a   "[No Name]"                    line 1    |
+      {3:Press ENTER or type command to continue}^           |
+    ]])
+
+    -- linked to StatusLine per default
+    feed_command("hi StatusLine guibg=Cyan")
+    feed_command("ls")
+    screen:expect([[
+                                                        |
+      {4:--------------------------------------------------}|
+      :ls                                               |
+        1 %a   "[No Name]"                    line 1    |
+      {3:Press ENTER or type command to continue}^           |
+    ]])
+
+    -- but can be unlinked
+    feed_command("hi clear MsgSeparator")
+    feed_command("hi MsgSeparator guibg=Magenta gui=bold")
+    feed_command("ls")
+    screen:expect([[
+                                                        |
+      {5:--------------------------------------------------}|
+      :ls                                               |
+        1 %a   "[No Name]"                    line 1    |
+      {3:Press ENTER or type command to continue}^           |
+    ]])
+
+    -- when display doesn't contain msgsep, these options have no effect
+    feed_command("set display-=msgsep")
+    feed_command("ls")
+    screen:expect([[
+      {1:~                                                 }|
+      {1:~                                                 }|
+      :ls                                               |
+        1 %a   "[No Name]"                    line 1    |
+      {3:Press ENTER or type command to continue}^           |
+    ]])
+  end)
+end)
+
 describe("'winhighlight' highlight", function()
   local screen
 
diff --git a/test/functional/ui/inccommand_spec.lua b/test/functional/ui/inccommand_spec.lua
index 8b0cb82365..27e4066d9f 100644
--- a/test/functional/ui/inccommand_spec.lua
+++ b/test/functional/ui/inccommand_spec.lua
@@ -63,6 +63,7 @@ local function common_setup(screen, inccommand, text)
     command("syntax on")
     command("set nohlsearch")
     command("hi Substitute guifg=red guibg=yellow")
+    command("set display-=msgsep")
     screen:attach()
     screen:set_default_attr_ids({
       [1]  = {foreground = Screen.colors.Fuchsia},
diff --git a/test/functional/ui/input_spec.lua b/test/functional/ui/input_spec.lua
index 8e62a37ef1..9bfc87d835 100644
--- a/test/functional/ui/input_spec.lua
+++ b/test/functional/ui/input_spec.lua
@@ -1,6 +1,7 @@
 local helpers = require('test.functional.helpers')(after_each)
 local clear, feed_command, nvim = helpers.clear, helpers.feed_command, helpers.nvim
 local feed, next_msg, eq = helpers.feed, helpers.next_msg, helpers.eq
+local command = helpers.command
 local expect = helpers.expect
 local write_file = helpers.write_file
 local Screen = require('test.functional.ui.screen')
@@ -137,6 +138,7 @@ describe('input non-printable chars', function()
       [3] = {bold = true, foreground = Screen.colors.SeaGreen4}
     })
     screen:attach()
+    command("set display-=msgsep")
 
     feed_command("e Xtest-overwrite")
     screen:expect([[
diff --git a/test/functional/ui/mouse_spec.lua b/test/functional/ui/mouse_spec.lua
index 05d5a6409a..debd324977 100644
--- a/test/functional/ui/mouse_spec.lua
+++ b/test/functional/ui/mouse_spec.lua
@@ -26,6 +26,7 @@ describe('ui/mouse/input', function()
       [4] = {reverse = true},
       [5] = {bold = true, reverse = true},
     })
+    command("set display-=msgsep")
     feed('itesting<cr>mouse<cr>support and selection<esc>')
     screen:expect([[
       testing                  |
diff --git a/test/functional/ui/output_spec.lua b/test/functional/ui/output_spec.lua
index 4246020fab..02ca566bd8 100644
--- a/test/functional/ui/output_spec.lua
+++ b/test/functional/ui/output_spec.lua
@@ -40,10 +40,10 @@ describe("shell command :!", function()
     --       to avoid triggering a UI flush.
     child_session.feed_data(":!printf foo; sleep 200\n")
     screen:expect([[
+                                                        |
       {4:~                                                 }|
       {4:~                                                 }|
-      {4:~                                                 }|
-      {4:~                                                 }|
+      {5:                                                  }|
       :!printf foo; sleep 200                           |
       foo                                               |
       {3:-- TERMINAL --}                                    |
@@ -99,6 +99,7 @@ describe("shell command :!", function()
     end
     local screen = Screen.new(50, 4)
     screen:attach()
+    command("set display-=msgsep")
     -- Print TAB chars. #2958
     feed([[:!printf '1\t2\t3'<CR>]])
     screen:expect([[
@@ -153,6 +154,7 @@ describe("shell command :!", function()
         [1] = {bold = true, foreground = Screen.colors.Blue1},
         [2] = {foreground = Screen.colors.Blue1},
         [3] = {bold = true, foreground = Screen.colors.SeaGreen4},
+        [4] = {bold = true, reverse = true},
       })
       screen:attach()
     end)
@@ -170,10 +172,10 @@ describe("shell command :!", function()
         or  [[:!ls bang_filter_spec    ]])
       feed([[\l]])
       screen:expect([[
+                                                             |
         {1:~                                                    }|
         {1:~                                                    }|
-        {1:~                                                    }|
-        {1:~                                                    }|
+        {4:                                                     }|
         ]]..result..[[                            |
         f1                                                   |
         f2                                                   |
@@ -187,9 +189,9 @@ describe("shell command :!", function()
       feed_command('!cat test/functional/fixtures/shell_data.txt')
       screen.bell = false
       screen:expect([[
+                                                             |
         {1:~                                                    }|
-        {1:~                                                    }|
-        {1:~                                                    }|
+        {4:                                                     }|
         :!cat test/functional/fixtures/shell_data.txt        |
         {2:^@^A^B^C^D^E^F^H}                                     |
         {2:^N^O^P^Q^R^S^T^U^V^W^X^Y^Z^[^\^]^^^_}                 |
@@ -213,8 +215,8 @@ describe("shell command :!", function()
       feed_command(cmd)
       -- Note: only the first example of split composed char works
       screen:expect([[
-        {1:~                                                    }|
-        {1:~                                                    }|
+                                                             |
+        {4:                                                     }|
         :]]..cmd..[[                                 |
         å                                                    |
         ref: å̲                                               |
diff --git a/test/functional/ui/screen_basic_spec.lua b/test/functional/ui/screen_basic_spec.lua
index bbdf576641..563d04416a 100644
--- a/test/functional/ui/screen_basic_spec.lua
+++ b/test/functional/ui/screen_basic_spec.lua
@@ -355,7 +355,8 @@ describe('Screen', function()
       ]])
     end)
 
-    it('execute command with multi-line output', function()
+    it('execute command with multi-line output without msgsep', function()
+      command("set display-=msgsep")
       feed(':ls<cr>')
       screen:expect([[
         {0:~                                                    }|
@@ -375,6 +376,28 @@ describe('Screen', function()
       ]])
       feed('<cr>') --  skip the "Press ENTER..." state or tests will hang
     end)
+
+    it('execute command with multi-line output and with msgsep', function()
+      command("set display+=msgsep")
+      feed(':ls<cr>')
+      screen:expect([[
+                                                             |
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {0:~                                                    }|
+        {1:                                                     }|
+        :ls                                                  |
+          1 %a   "[No Name]"                    line 1       |
+        {7:Press ENTER or type command to continue}^              |
+      ]])
+      feed('<cr>') --  skip the "Press ENTER..." state or tests will hang
+    end)
   end)
 
   describe('scrolling and clearing', function()
@@ -573,6 +596,7 @@ describe('Screen', function()
       command('nnoremap <F1> :echo "TEST"<CR>')
       feed(':ls<CR>')
       screen:expect([[
+                                                             |
         {0:~                                                    }|
         {0:~                                                    }|
         {0:~                                                    }|
@@ -582,8 +606,7 @@ describe('Screen', function()
         {0:~                                                    }|
         {0:~                                                    }|
         {0:~                                                    }|
-        {0:~                                                    }|
-        {0:~                                                    }|
+        {1:                                                     }|
         :ls                                                  |
           1 %a   "[No Name]"                    line 1       |
         {7:Press ENTER or type command to continue}^              |