27 files changed, 213 insertions, 330 deletions

diff --git a/src/nvim/autocmd.c b/src/nvim/autocmd.c
index 439704d120..81d495ee27 100644
--- a/src/nvim/autocmd.c
+++ b/src/nvim/autocmd.c
@@ -2720,7 +2720,7 @@ static void do_autocmd_focusgained(bool gained)
       redrawcmdline();
     } else if ((State & MODE_NORMAL) || (State & MODE_INSERT)) {
       if (must_redraw != 0) {
-        update_screen(0);
+        update_screen();
       }
 
       setcursor();
diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index 65b07cc17b..a29d022606 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -2810,7 +2810,7 @@ void wildmenu_cleanup(CmdlineInfo *cclp)
     p_ls = save_p_ls;
     p_wmh = save_p_wmh;
     last_status(false);
-    update_screen(UPD_VALID);  // redraw the screen NOW
+    update_screen();  // redraw the screen NOW
     redrawcmd();
     save_p_ls = -1;
     wild_menu_showing = 0;
diff --git a/src/nvim/drawscreen.c b/src/nvim/drawscreen.c
index 8c18bf75e5..15a7294496 100644
--- a/src/nvim/drawscreen.c
+++ b/src/nvim/drawscreen.c
@@ -97,7 +97,7 @@ typedef enum {
 
 static bool redraw_popupmenu = false;
 static bool msg_grid_invalid = false;
-static bool resizing = false;
+static bool resizing_autocmd = false;
 
 static char *provider_err = NULL;
 
@@ -115,7 +115,7 @@ void conceal_check_cursor_line(void)
   }
 }
 
-/// Resize the screen to Rows and Columns.
+/// Resize default_grid to Rows and Columns.
 ///
 /// Allocate default_grid.chars[] and other grid arrays.
 ///
@@ -125,19 +125,18 @@ void conceal_check_cursor_line(void)
 /// default_grid.Columns to access items in default_grid.chars[].  Use Rows
 /// and Columns for positioning text etc. where the final size of the screen is
 /// needed.
-void screenalloc(void)
+bool default_grid_alloc(void)
 {
+  static bool resizing = false;
+
   // It's possible that we produce an out-of-memory message below, which
   // will cause this function to be called again.  To break the loop, just
   // return here.
   if (resizing) {
-    return;
+    return false;
   }
   resizing = true;
 
-  int retry_count = 0;
-
-retry:
   // Allocation of the screen buffers is done only when the size changes and
   // when Rows and Columns have been set and we have started doing full
   // screen stuff.
@@ -148,24 +147,9 @@ retry:
       || Columns == 0
       || (!full_screen && default_grid.chars == NULL)) {
     resizing = false;
-    return;
-  }
-
-  // Note that the window sizes are updated before reallocating the arrays,
-  // thus we must not redraw here!
-  RedrawingDisabled++;
-
-  // win_new_screensize will recompute floats position, but tell the
-  // compositor to not redraw them yet
-  ui_comp_set_screen_valid(false);
-  if (msg_grid.chars) {
-    msg_grid_invalid = true;
+    return false;
   }
 
-  win_new_screensize();      // fit the windows in the new sized screen
-
-  comp_col();           // recompute columns for shown command and ruler
-
   // We're changing the size of the screen.
   // - Allocate new arrays for default_grid
   // - Move lines from the old arrays into the new arrays, clear extra
@@ -193,26 +177,13 @@ retry:
   default_grid.col_offset = 0;
   default_grid.handle = DEFAULT_GRID_HANDLE;
 
-  must_redraw = UPD_CLEAR;  // need to clear the screen later
-
-  RedrawingDisabled--;
-
-  // Do not apply autocommands more than 3 times to avoid an endless loop
-  // in case applying autocommands always changes Rows or Columns.
-  if (starting == 0 && ++retry_count <= 3) {
-    apply_autocmds(EVENT_VIMRESIZED, NULL, NULL, false, curbuf);
-    // In rare cases, autocommands may have altered Rows or Columns,
-    // jump back to check if we need to allocate the screen again.
-    goto retry;
-  }
-
   resizing = false;
+  return true;
 }
 
 void screenclear(void)
 {
   check_for_delay(false);
-  screenalloc();  // allocate screen buffers if size changed
 
   int i;
 
@@ -281,13 +252,6 @@ void screen_resize(int width, int height)
     return;
   }
 
-  // curwin->w_buffer can be NULL when we are closing a window and the
-  // buffer has already been closed and removing a scrollbar causes a resize
-  // event. Don't resize then, it will happen after entering another buffer.
-  if (curwin->w_buffer == NULL) {
-    return;
-  }
-
   resizing_screen = true;
 
   Rows = height;
@@ -301,16 +265,54 @@ void screen_resize(int width, int height)
   width = Columns;
   p_lines = Rows;
   p_columns = Columns;
-  ui_call_grid_resize(1, width, height);
 
-  /// The window layout used to be adjusted here, but it now happens in
-  /// screenalloc() (also invoked from screenclear()).  That is because the
-  /// recursize "resizing_screen" check above may skip this, but not screenalloc().
+  // was invoked recursively from a VimResized autocmd, handled as a loop below
+  if (resizing_autocmd) {
+    return;
+  }
+
+  int retry_count = 0;
+  resizing_autocmd = true;
+
+  bool retry_resize = true;
+  while (retry_resize) {
+    retry_resize = default_grid_alloc();
 
-  if (State != MODE_ASKMORE && State != MODE_EXTERNCMD && State != MODE_CONFIRM) {
-    screenclear();
+    // Do not apply autocommands more than 3 times to avoid an endless loop
+    // in case applying autocommands always changes Rows or Columns.
+    if (++retry_count > 3) {
+      break;
+    }
+
+    if (retry_resize) {
+      // In rare cases, autocommands may have altered Rows or Columns,
+      // retry to check if we need to allocate the screen again.
+      apply_autocmds(EVENT_VIMRESIZED, NULL, NULL, false, curbuf);
+    }
   }
 
+  resizing_autocmd = false;
+
+  ui_call_grid_resize(1, width, height);
+
+  // win_new_screensize will recompute floats position, but tell the
+  // compositor to not redraw them yet
+  ui_comp_set_screen_valid(false);
+  if (msg_grid.chars) {
+    msg_grid_invalid = true;
+  }
+
+  // Note that the window sizes are updated before reallocating the arrays,
+  // thus we must not redraw here!
+  RedrawingDisabled++;
+
+  win_new_screensize();      // fit the windows in the new sized screen
+
+  comp_col();           // recompute columns for shown command and ruler
+
+  RedrawingDisabled--;
+  redraw_all_later(UPD_CLEAR);
+
   if (starting != NO_SCREEN) {
     maketitle();
 
@@ -320,14 +322,11 @@ void screen_resize(int width, int height)
     // We only redraw when it's needed:
     // - While at the more prompt or executing an external command, don't
     //   redraw, but position the cursor.
-    // - While editing the command line, only redraw that.
+    // - While editing the command line, only redraw that. TODO: lies
     // - in Ex mode, don't redraw anything.
     // - Otherwise, redraw right now, and position the cursor.
-    // Always need to call update_screen() or screenalloc(), to make
-    // sure Rows/Columns and the size of the screen is correct!
     if (State == MODE_ASKMORE || State == MODE_EXTERNCMD || State == MODE_CONFIRM
         || exmode_active) {
-      screenalloc();
       if (msg_grid.chars) {
         msg_grid_validate();
       }
@@ -341,7 +340,7 @@ void screen_resize(int width, int height)
       }
       if (State & MODE_CMDLINE) {
         redraw_popupmenu = false;
-        update_screen(UPD_NOT_VALID);
+        update_screen();
         redrawcmdline();
         if (pum_drawn()) {
           cmdline_pum_display(false);
@@ -350,12 +349,12 @@ void screen_resize(int width, int height)
         update_topline(curwin);
         if (pum_drawn()) {
           // TODO(bfredl): ins_compl_show_pum wants to redraw the screen first.
-          // For now make sure the nested update_screen(0) won't redraw the
+          // For now make sure the nested update_screen() won't redraw the
           // pum at the old position. Try to untangle this later.
           redraw_popupmenu = false;
           ins_compl_show_pum();
         }
-        update_screen(UPD_NOT_VALID);
+        update_screen();
         if (redrawing()) {
           setcursor();
         }
@@ -370,9 +369,7 @@ void screen_resize(int width, int height)
 ///
 /// Most code shouldn't call this directly, rather use redraw_later() and
 /// and redraw_all_later() to mark parts of the screen as needing a redraw.
-///
-/// @param type set to a UPD_NOT_VALID to force redraw of entire screen
-int update_screen(int type)
+int update_screen(void)
 {
   static bool did_intro = false;
   bool is_stl_global = global_stl_height() > 0;
@@ -380,7 +377,7 @@ int update_screen(int type)
   // Don't do anything if the screen structures are (not yet) valid.
   // A VimResized autocmd can invoke redrawing in the middle of a resize,
   // which would bypass the checks in screen_resize for popupmenu etc.
-  if (!default_grid.chars || resizing) {
+  if (resizing_autocmd || !default_grid.chars) {
     return FAIL;
   }
 
@@ -389,41 +386,25 @@ int update_screen(int type)
     diff_redraw(true);
   }
 
-  // TODO(bfredl): completely get rid of using update_screen(UPD_XX_VALID)
-  // to redraw curwin
-  int curwin_type = MIN(type, UPD_NOT_VALID);
-
-  if (must_redraw) {
-    if (type < must_redraw) {       // use maximal type
-      type = must_redraw;
-    }
-
-    // must_redraw is reset here, so that when we run into some weird
-    // reason to redraw while busy redrawing (e.g., asynchronous
-    // scrolling), or update_topline() in win_update() will cause a
-    // scroll, or a decoration provider requires a redraw, the screen
-    // will be redrawn later or in win_update().
-    must_redraw = 0;
-  }
-
-  // Need to update w_lines[].
-  if (curwin->w_lines_valid == 0 && type < UPD_NOT_VALID) {
-    type = UPD_NOT_VALID;
-  }
-
   // Postpone the redrawing when it's not needed and when being called
   // recursively.
   if (!redrawing() || updating_screen) {
-    must_redraw = type;
-    if (type > UPD_INVERTED_ALL) {
-      curwin->w_lines_valid = 0;  // don't use w_lines[].wl_size now
-    }
     return FAIL;
   }
+
+  int type = must_redraw;
+
+  // must_redraw is reset here, so that when we run into some weird
+  // reason to redraw while busy redrawing (e.g., asynchronous
+  // scrolling), or update_topline() in win_update() will cause a
+  // scroll, or a decoration provider requires a redraw, the screen
+  // will be redrawn later or in win_update().
+  must_redraw = 0;
+
   updating_screen = 1;
 
-  display_tick++;           // let syntax code know we're in a next round of
-                            // display updating
+  display_tick++;  // let syntax code know we're in a next round of
+                   // display updating
 
   // Tricky: vim code can reset msg_scrolled behind our back, so need
   // separate bookkeeping for now.
@@ -447,75 +428,41 @@ int update_screen(int type)
                         msg_grid.cols, false);
       }
     }
-    if (msg_use_msgsep()) {
-      msg_grid.throttled = false;
-      bool was_invalidated = false;
+    msg_grid.throttled = false;
+    bool was_invalidated = false;
 
-      // UPD_CLEAR is already handled
-      if (type == UPD_NOT_VALID && !ui_has(kUIMultigrid) && msg_scrolled) {
-        was_invalidated = ui_comp_set_screen_valid(false);
-        for (int i = valid; i < Rows - p_ch; i++) {
-          grid_clear_line(&default_grid, default_grid.line_offset[i],
-                          Columns, false);
+    // UPD_CLEAR is already handled
+    if (type == UPD_NOT_VALID && !ui_has(kUIMultigrid) && msg_scrolled) {
+      was_invalidated = ui_comp_set_screen_valid(false);
+      for (int i = valid; i < Rows - p_ch; i++) {
+        grid_clear_line(&default_grid, default_grid.line_offset[i],
+                        Columns, false);
+      }
+      FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
+        if (wp->w_floating) {
+          continue;
         }
-        FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
-          if (wp->w_floating) {
-            continue;
-          }
-          if (W_ENDROW(wp) > valid) {
-            // TODO(bfredl): too pessimistic. type could be UPD_NOT_VALID
-            // only because windows that are above the separator.
-            wp->w_redr_type = MAX(wp->w_redr_type, UPD_NOT_VALID);
-          }
-          if (!is_stl_global && W_ENDROW(wp) + wp->w_status_height > valid) {
-            wp->w_redr_status = true;
-          }
+        if (W_ENDROW(wp) > valid) {
+          // TODO(bfredl): too pessimistic. type could be UPD_NOT_VALID
+          // only because windows that are above the separator.
+          wp->w_redr_type = MAX(wp->w_redr_type, UPD_NOT_VALID);
         }
-        if (is_stl_global && Rows - p_ch - 1 > valid) {
-          curwin->w_redr_status = true;
+        if (!is_stl_global && W_ENDROW(wp) + wp->w_status_height > valid) {
+          wp->w_redr_status = true;
         }
       }
-      msg_grid_set_pos(Rows - (int)p_ch, false);
-      msg_grid_invalid = false;
-      if (was_invalidated) {
-        // screen was only invalid for the msgarea part.
-        // @TODO(bfredl): using the same "valid" flag
-        // for both messages and floats moving is bit of a mess.
-        ui_comp_set_screen_valid(true);
-      }
-    } else if (type != UPD_CLEAR) {
-      if (msg_scrolled > Rows - 5) {  // redrawing is faster
-        type = UPD_NOT_VALID;
-        curwin_type = UPD_NOT_VALID;
-      } else {
-        check_for_delay(false);
-        grid_ins_lines(&default_grid, 0, msg_scrolled, Rows, 0, Columns);
-        FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
-          if (wp->w_floating) {
-            continue;
-          }
-          if (wp->w_winrow < msg_scrolled) {
-            if (W_ENDROW(wp) > msg_scrolled
-                && wp->w_redr_type < UPD_REDRAW_TOP
-                && wp->w_lines_valid > 0
-                && wp->w_topline == wp->w_lines[0].wl_lnum) {
-              wp->w_upd_rows = msg_scrolled - wp->w_winrow;
-              wp->w_redr_type = UPD_REDRAW_TOP;
-            } else {
-              wp->w_redr_type = UPD_NOT_VALID;
-              if (wp->w_winrow + wp->w_winbar_height <= msg_scrolled) {
-                wp->w_redr_status = true;
-              }
-            }
-          }
-        }
-        if (is_stl_global && Rows - p_ch - 1 <= msg_scrolled) {
-          curwin->w_redr_status = true;
-        }
-        redraw_cmdline = true;
-        redraw_tabline = true;
+      if (is_stl_global && Rows - p_ch - 1 > valid) {
+        curwin->w_redr_status = true;
       }
     }
+    msg_grid_set_pos(Rows - (int)p_ch, false);
+    msg_grid_invalid = false;
+    if (was_invalidated) {
+      // screen was only invalid for the msgarea part.
+      // @TODO(bfredl): using the same "valid" flag
+      // for both messages and floats moving is bit of a mess.
+      ui_comp_set_screen_valid(true);
+    }
     msg_scrolled = 0;
     msg_scrolled_at_flush = 0;
     need_wait_return = false;
@@ -535,7 +482,8 @@ int update_screen(int type)
   }
 
   if (type == UPD_CLEAR) {          // first clear screen
-    screenclear();              // will reset clear_cmdline
+    screenclear();  // will reset clear_cmdline
+                    // and set UPD_NOT_VALID for each window
     cmdline_screen_cleared();   // clear external cmdline state
     type = UPD_NOT_VALID;
     // must_redraw may be set indirectly, avoid another redraw later
@@ -545,9 +493,8 @@ int update_screen(int type)
     default_grid.valid = true;
   }
 
-  // After disabling msgsep the grid might not have been deallocated yet,
-  // hence we also need to check msg_grid.chars
-  if (type == UPD_NOT_VALID && (msg_use_grid() || msg_grid.chars)) {
+  // might need to clear space on default_grid for the message area.
+  if (type == UPD_NOT_VALID && clear_cmdline && !ui_has(kUIMessages)) {
     grid_fill(&default_grid, Rows - (int)p_ch, Rows, 0, Columns, ' ', ' ', 0);
   }
 
@@ -576,28 +523,6 @@ int update_screen(int type)
     curwin->w_redr_type = UPD_NOT_VALID;
   }
 
-  // Only start redrawing if there is really something to do.
-  // TODO(bfredl): more curwin special casing to get rid of.
-  // Change update_screen(UPD_INVERTED) to a wrapper function
-  // perhaps?
-  if (curwin_type == UPD_INVERTED) {
-    update_curswant();
-  }
-  if (curwin->w_redr_type < curwin_type
-      && !((curwin_type == UPD_VALID
-            && curwin->w_lines[0].wl_valid
-            && curwin->w_topfill == curwin->w_old_topfill
-            && curwin->w_botfill == curwin->w_old_botfill
-            && curwin->w_topline == curwin->w_lines[0].wl_lnum)
-           || (curwin_type == UPD_INVERTED
-               && VIsual_active
-               && curwin->w_old_cursor_lnum == curwin->w_cursor.lnum
-               && curwin->w_old_visual_mode == VIsual_mode
-               && (curwin->w_valid & VALID_VIRTCOL)
-               && curwin->w_old_curswant == curwin->w_curswant))) {
-    curwin->w_redr_type = curwin_type;
-  }
-
   // Redraw the tab pages line if needed.
   if (redraw_tabline || type >= UPD_NOT_VALID) {
     update_window_hl(curwin, type >= UPD_NOT_VALID);
@@ -2034,7 +1959,7 @@ win_update_start:
   }
 }
 
-/// Redraw a window later, with update_screen(type).
+/// Redraw a window later, with wp->w_redr_type >= type.
 ///
 /// Set must_redraw only if not already set to a higher value.
 /// e.g. if must_redraw is UPD_CLEAR, type UPD_NOT_VALID will do nothing.
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index a165078bdf..781e9e3553 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -1286,7 +1286,7 @@ void ins_redraw(bool ready)
     // a "(".  The autocommand may also require a redraw, so it's done
     // again below, unfortunately.
     if (syntax_present(curwin) && must_redraw) {
-      update_screen(0);
+      update_screen();
     }
     // Make sure curswant is correct, an autocommand may call
     // getcurpos()
@@ -1348,7 +1348,7 @@ void ins_redraw(bool ready)
 
   pum_check_clear();
   if (must_redraw) {
-    update_screen(0);
+    update_screen();
   } else if (clear_cmdline || redraw_cmdline) {
     showmode();  // clear cmdline and show mode
   }
diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 77feddbbf9..ea51cac163 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -3876,7 +3876,8 @@ static int do_sub(exarg_T *eap, proftime_T timeout, long cmdpreview_ns, handle_T
 
               update_topline(curwin);
               validate_cursor();
-              update_screen(UPD_SOME_VALID);
+              redraw_later(curwin, UPD_SOME_VALID);
+              update_screen();
               highlight_match = false;
               redraw_later(curwin, UPD_SOME_VALID);
 
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 987fb439d7..5591b5f55d 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -254,7 +254,7 @@ void do_exmode(void)
   RedrawingDisabled--;
   no_wait_return--;
   redraw_all_later(UPD_NOT_VALID);
-  update_screen(UPD_NOT_VALID);
+  update_screen();
   need_wait_return = false;
   msg_scroll = save_msg_scroll;
 }
@@ -6090,9 +6090,10 @@ static void ex_redraw(exarg_T *eap)
   if (eap->forceit) {
     redraw_all_later(UPD_NOT_VALID);
     redraw_cmdline = true;
+  } else if (VIsual_active) {
+    redraw_curbuf_later(UPD_INVERTED);
   }
-  update_screen(eap->forceit ? UPD_NOT_VALID
-                : VIsual_active ? UPD_INVERTED : 0);
+  update_screen();
   if (need_maketitle) {
     maketitle();
   }
@@ -6123,16 +6124,16 @@ static void ex_redrawstatus(exarg_T *eap)
   } else {
     status_redraw_curbuf();
   }
-  if (msg_scrolled && !msg_use_msgsep() && (State & MODE_CMDLINE)) {
-    return;  // redraw later
-  }
 
   RedrawingDisabled = 0;
   p_lz = false;
   if (State & MODE_CMDLINE) {
     redraw_statuslines();
   } else {
-    update_screen(VIsual_active ? UPD_INVERTED : 0);
+    if (VIsual_active) {
+      redraw_curbuf_later(UPD_INVERTED);
+    }
+    update_screen();
   }
   RedrawingDisabled = r;
   p_lz = p;
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 4b54b58ac1..6883dc5b14 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -501,7 +501,8 @@ static void may_do_incsearch_highlighting(int firstc, long count, incsearch_stat
     curwin->w_redr_status = true;
   }
 
-  update_screen(UPD_SOME_VALID);
+  redraw_later(curwin, UPD_SOME_VALID);
+  update_screen();
   highlight_match = false;
   restore_last_search_pattern();
 
@@ -588,7 +589,7 @@ static void finish_incsearch_highlighting(int gotesc, incsearch_state_T *s, bool
     validate_cursor();          // needed for TAB
     redraw_all_later(UPD_SOME_VALID);
     if (call_update_screen) {
-      update_screen(UPD_SOME_VALID);
+      update_screen();
     }
   }
 }
@@ -774,7 +775,7 @@ static uint8_t *command_line_enter(int firstc, long count, int indent, bool init
 
   // Redraw the statusline in case it uses the current mode using the mode()
   // function.
-  if (!cmd_silent && (msg_scrolled == 0 || msg_use_msgsep())) {
+  if (!cmd_silent) {
     bool found_one = false;
 
     FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
@@ -1376,7 +1377,8 @@ static int may_do_command_line_next_incsearch(int firstc, long count, incsearch_
     validate_cursor();
     highlight_match = true;
     save_viewstate(curwin, &s->old_viewstate);
-    update_screen(UPD_NOT_VALID);
+    redraw_later(curwin, UPD_NOT_VALID);
+    update_screen();
     highlight_match = false;
     redrawcmdline();
     curwin->w_cursor = s->match_end;
@@ -2336,7 +2338,7 @@ static bool cmdpreview_may_show(CommandLineState *s)
   if (cmdpreview_type != 0) {
     int save_rd = RedrawingDisabled;
     RedrawingDisabled = 0;
-    update_screen(UPD_SOME_VALID);
+    update_screen();
     RedrawingDisabled = save_rd;
   }
 
@@ -2406,7 +2408,9 @@ static int command_line_changed(CommandLineState *s)
   } else {
     cmdpreview = false;
     if (prev_cmdpreview) {
-      update_screen(UPD_SOME_VALID);  // Clear 'inccommand' preview.
+      // TODO(bfredl): add an immediate redraw flag for cmdline mode which will trigger
+      // at next wait-for-input
+      update_screen();  // Clear 'inccommand' preview.
     }
     if (s->xpc.xp_context == EXPAND_NOTHING && (KeyTyped || vpeekc() == NUL)) {
       may_do_incsearch_highlighting(s->firstc, s->count, &s->is_state);
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 76317298dc..b31b8336aa 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -1721,13 +1721,6 @@ failed:
       appended_lines_mark(from, linecnt);
     }
 
-    // If we were reading from the same terminal as where messages go,
-    // the screen will have been messed up.
-    // Switch on raw mode now and clear the screen.
-    if (read_stdin) {
-      screenclear();
-    }
-
     if (got_int) {
       if (!(flags & READ_DUMMY)) {
         filemess(curbuf, sfname, _(e_interr), 0);
diff --git a/src/nvim/generators/gen_options.lua b/src/nvim/generators/gen_options.lua
index 24b4739fc7..6dba6552b3 100644
--- a/src/nvim/generators/gen_options.lua
+++ b/src/nvim/generators/gen_options.lua
@@ -34,7 +34,6 @@ local redraw_flags={
   current_window_only='P_RWINONLY',
   current_buffer='P_RBUF',
   all_windows='P_RALL',
-  everything='P_RCLR',
   curswant='P_CURSWANT',
   ui_option='P_UI_OPTION',
 }
diff --git a/src/nvim/getchar.c b/src/nvim/getchar.c
index ef66e2d355..4135065787 100644
--- a/src/nvim/getchar.c
+++ b/src/nvim/getchar.c
@@ -2601,7 +2601,7 @@ static int vgetorpeek(bool advance)
         // input buffer (e.g., termresponse).
         if (((State & MODE_INSERT) != 0 || p_lz) && (State & MODE_CMDLINE) == 0
             && advance && must_redraw != 0 && !need_wait_return) {
-          update_screen(0);
+          update_screen();
           setcursor();  // put cursor back where it belongs
         }
 
diff --git a/src/nvim/insexpand.c b/src/nvim/insexpand.c
index 1426f28453..da1063f699 100644
--- a/src/nvim/insexpand.c
+++ b/src/nvim/insexpand.c
@@ -1228,7 +1228,7 @@ void ins_compl_show_pum(void)
   do_cmdline_cmd("if exists('g:loaded_matchparen')|3match none|endif");
 
   // Update the screen before drawing the popup menu over it.
-  update_screen(0);
+  update_screen();
 
   int cur = -1;
   bool array_changed = false;
@@ -1648,7 +1648,7 @@ int ins_compl_bs(void)
     ins_compl_restart();
   }
 
-  // ins_compl_restart() calls update_screen(0) which may invalidate the pointer
+  // ins_compl_restart() calls update_screen() which may invalidate the pointer
   // TODO(bfredl): get rid of random update_screen() calls deep inside completion logic
   line = get_cursor_line_ptr();
 
@@ -1759,7 +1759,7 @@ static void ins_compl_restart(void)
   // update screen before restart.
   // so if complete is blocked,
   // will stay to the last popup menu and reduce flicker
-  update_screen(0);
+  update_screen();  // TODO(bfredl): no.
   ins_compl_free();
   compl_started = false;
   compl_matches = 0;
@@ -2048,7 +2048,7 @@ static bool ins_compl_stop(const int c, const int prev_mode, bool retval)
   if (c == Ctrl_C && cmdwin_type != 0) {
     // Avoid the popup menu remains displayed when leaving the
     // command line window.
-    update_screen(0);
+    update_screen();
   }
 
   // Indent now if a key was typed that is in 'cinkeys'.
@@ -3533,7 +3533,7 @@ static int ins_compl_next(bool allow_get_expansion, int count, bool insert_match
 
   if (!allow_get_expansion) {
     // redraw to show the user what was inserted
-    update_screen(0);
+    update_screen();  // TODO(bfredl): no!
 
     // display the updated popup menu
     ins_compl_show_pum();
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 1119cee6ad..673b177463 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -185,11 +185,11 @@ void early_init(mparm_T *paramp)
   init_locale();
 #endif
 
-  // Allocate the first window and buffer.
-  // Can't do anything without it, exit when it fails.
-  if (!win_alloc_first()) {
-    os_exit(0);
-  }
+  // tabpage local options (p_ch) must be set before allocating first tabpage.
+  set_init_tablocal();
+
+  // Allocate the first tabpage, window and buffer.
+  win_alloc_first();
   TIME_MSG("init first window");
 
   alist_init(&global_alist);    // Init the argument list to empty.
@@ -314,7 +314,7 @@ int main(int argc, char **argv)
   assert(p_ch >= 0 && Rows >= p_ch && Rows - p_ch <= INT_MAX);
   cmdline_row = (int)(Rows - p_ch);
   msg_row = cmdline_row;
-  screenalloc();  // allocate screen buffers
+  default_grid_alloc();  // allocate screen buffers
   set_init_2(headless_mode);
   TIME_MSG("inits 2");
 
@@ -346,13 +346,14 @@ int main(int argc, char **argv)
       ui_builtin_start();
     }
     TIME_MSG("done waiting for UI");
-
-    // prepare screen now, so external UIs can display messages
-    starting = NO_BUFFERS;
-    screenclear();
-    TIME_MSG("init screen for UI");
   }
 
+  // prepare screen now
+  starting = NO_BUFFERS;
+  screenclear();
+  win_new_screensize();
+  TIME_MSG("clear screen");
+
   if (ui_client_channel_id) {
     ui_client_init(ui_client_channel_id);
     ui_client_execute(ui_client_channel_id);
@@ -361,8 +362,8 @@ int main(int argc, char **argv)
 
   // Default mappings (incl. menus)
   Error err = ERROR_INIT;
-  Object o = nlua_exec(STATIC_CSTR_AS_STRING("return vim._init_default_mappings()"),
-                       (Array)ARRAY_DICT_INIT, &err);
+  Object o = NLUA_EXEC_STATIC("return vim._init_default_mappings()",
+                              (Array)ARRAY_DICT_INIT, &err);
   assert(!ERROR_SET(&err));
   api_clear_error(&err);
   assert(o.type == kObjectTypeNil);
@@ -432,10 +433,8 @@ int main(int argc, char **argv)
     p_ut = 1;
   }
 
-  //
   // Read in registers, history etc, from the ShaDa file.
   // This is where v:oldfiles gets filled.
-  //
   if (*p_shada != NUL) {
     shada_read_everything(NULL, false, true);
     TIME_MSG("reading ShaDa");
@@ -474,14 +473,7 @@ int main(int argc, char **argv)
 
   setmouse();  // may start using the mouse
 
-  if (exmode_active || use_remote_ui || use_builtin_ui) {
-    // Don't clear the screen when starting in Ex mode, or when a UI might have
-    // displayed messages.
-    redraw_later(curwin, UPD_VALID);
-  } else {
-    screenclear();  // clear screen
-    TIME_MSG("clearing screen");
-  }
+  redraw_later(curwin, UPD_VALID);
 
   no_wait_return = true;
 
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 060d969f4b..fef5055c84 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -153,8 +153,7 @@ void msg_grid_set_pos(int row, bool scrolled)
 
 bool msg_use_grid(void)
 {
-  return default_grid.chars && msg_use_msgsep()
-         && !ui_has(kUIMessages);
+  return default_grid.chars && !ui_has(kUIMessages);
 }
 
 void msg_grid_validate(void)
@@ -172,19 +171,17 @@ void msg_grid_validate(void)
     xfree(msg_grid.dirty_col);
     msg_grid.dirty_col = xcalloc((size_t)Rows, sizeof(*msg_grid.dirty_col));
 
-    // Tricky: allow resize while pager is active
-    int pos = msg_scrolled ? msg_grid_pos : max_rows;
+    // Tricky: allow resize while pager or ex mode is active
+    int pos = MAX(max_rows - msg_scrolled, 0);
+    msg_grid.throttled = false;  // don't throttle in 'cmdheight' area
+    msg_grid_set_pos(pos, msg_scrolled);
     ui_comp_put_grid(&msg_grid, pos, 0, msg_grid.rows, msg_grid.cols,
                      false, true);
     ui_call_grid_resize(msg_grid.handle, msg_grid.cols, msg_grid.rows);
 
-    msg_grid.throttled = false;  // don't throttle in 'cmdheight' area
     msg_scrolled_at_flush = msg_scrolled;
     msg_grid.focusable = false;
     msg_grid_adj.target = &msg_grid;
-    if (!msg_scrolled) {
-      msg_grid_set_pos(max_rows, false);
-    }
   } else if (!should_alloc && msg_grid.chars) {
     ui_comp_remove_grid(&msg_grid);
     grid_free(&msg_grid);
@@ -1159,10 +1156,6 @@ void wait_return(int redraw)
     c = CAR;                    // no need for a return in ex mode
     got_int = false;
   } else {
-    // Make sure the hit-return prompt is on screen when 'guioptions' was
-    // just changed.
-    screenalloc();
-
     State = MODE_HITRETURN;
     setmouse();
     cmdline_row = msg_row;
@@ -2340,13 +2333,6 @@ int msg_scrollsize(void)
   return msg_scrolled + (int)p_ch + ((p_ch > 0 || msg_scrolled > 1) ? 1 : 0);
 }
 
-bool msg_use_msgsep(void)
-{
-  // the full-screen scroll behavior doesn't really make sense with
-  // 'ext_multigrid'
-  return (dy_flags & DY_MSGSEP) || p_ch == 0 || ui_has(kUIMultigrid);
-}
-
 bool msg_do_throttle(void)
 {
   return msg_use_grid() && !(rdb_flags & RDB_NOTHROTTLE);
@@ -2359,23 +2345,19 @@ void msg_scroll_up(bool may_throttle, bool zerocmd)
     msg_grid.throttled = true;
   }
   msg_did_scroll = true;
-  if (msg_use_msgsep()) {
-    if (msg_grid_pos > 0) {
-      msg_grid_set_pos(msg_grid_pos - 1, !zerocmd);
-
-      // When displaying the first line with cmdheight=0, we need to draw over
-      // the existing last line of the screen.
-      if (zerocmd && msg_grid.chars) {
-        grid_clear_line(&msg_grid, msg_grid.line_offset[0], msg_grid.cols, false);
-      }
-    } else {
-      grid_del_lines(&msg_grid, 0, 1, msg_grid.rows, 0, msg_grid.cols);
-      memmove(msg_grid.dirty_col, msg_grid.dirty_col + 1,
-              (size_t)(msg_grid.rows - 1) * sizeof(*msg_grid.dirty_col));
-      msg_grid.dirty_col[msg_grid.rows - 1] = 0;
+  if (msg_grid_pos > 0) {
+    msg_grid_set_pos(msg_grid_pos - 1, !zerocmd);
+
+    // When displaying the first line with cmdheight=0, we need to draw over
+    // the existing last line of the screen.
+    if (zerocmd && msg_grid.chars) {
+      grid_clear_line(&msg_grid, msg_grid.line_offset[0], msg_grid.cols, false);
     }
   } else {
-    grid_del_lines(&msg_grid_adj, 0, 1, Rows, 0, Columns);
+    grid_del_lines(&msg_grid, 0, 1, msg_grid.rows, 0, msg_grid.cols);
+    memmove(msg_grid.dirty_col, msg_grid.dirty_col + 1,
+            (size_t)(msg_grid.rows - 1) * sizeof(*msg_grid.dirty_col));
+    msg_grid.dirty_col[msg_grid.rows - 1] = 0;
   }
 
   grid_fill(&msg_grid_adj, Rows - 1, Rows, 0, Columns, ' ', ' ', HL_ATTR(HLF_MSG));
@@ -2440,21 +2422,17 @@ void msg_reset_scroll(void)
   }
   // TODO(bfredl): some duplicate logic with update_screen(). Later on
   // we should properly disentangle message clear with full screen redraw.
-  if (msg_use_grid()) {
-    msg_grid.throttled = false;
-    // TODO(bfredl): risk for extra flicker i e with
-    // "nvim -o has_swap also_has_swap"
-    msg_grid_set_pos(Rows - (int)p_ch, false);
-    clear_cmdline = true;
-    if (msg_grid.chars) {
-      // non-displayed part of msg_grid is considered invalid.
-      for (int i = 0; i < MIN(msg_scrollsize(), msg_grid.rows); i++) {
-        grid_clear_line(&msg_grid, msg_grid.line_offset[i],
-                        msg_grid.cols, false);
-      }
+  msg_grid.throttled = false;
+  // TODO(bfredl): risk for extra flicker i e with
+  // "nvim -o has_swap also_has_swap"
+  msg_grid_set_pos(Rows - (int)p_ch, false);
+  clear_cmdline = true;
+  if (msg_grid.chars) {
+    // non-displayed part of msg_grid is considered invalid.
+    for (int i = 0; i < MIN(msg_scrollsize(), msg_grid.rows); i++) {
+      grid_clear_line(&msg_grid, msg_grid.line_offset[i],
+                      msg_grid.cols, false);
     }
-  } else {
-    redraw_all_later(UPD_NOT_VALID);
   }
   msg_scrolled = 0;
   msg_scrolled_at_flush = 0;
diff --git a/src/nvim/move.c b/src/nvim/move.c
index 481746881b..9d1d2e9cad 100644
--- a/src/nvim/move.c
+++ b/src/nvim/move.c
@@ -130,16 +130,6 @@ static void redraw_for_cursorcolumn(win_T *wp)
   }
 }
 
-// Update curwin->w_topline and redraw if necessary.
-// Used to update the screen before printing a message.
-void update_topline_redraw(void)
-{
-  update_topline(curwin);
-  if (must_redraw) {
-    update_screen(0);
-  }
-}
-
 // Update curwin->w_topline to move the cursor onto the screen.
 void update_topline(win_T *wp)
 {
diff --git a/src/nvim/normal.c b/src/nvim/normal.c
index 95665053b3..ec89e25b97 100644
--- a/src/nvim/normal.c
+++ b/src/nvim/normal.c
@@ -636,7 +636,7 @@ static void normal_redraw_mode_message(NormalState *s)
     // Showmode() will clear keep_msg, but we want to use it anyway.
     // First update w_topline.
     setcursor();
-    update_screen(0);
+    update_screen();
     // now reset it, otherwise it's put in the history again
     keep_msg = kmsg;
 
@@ -1284,9 +1284,9 @@ static void normal_redraw(NormalState *s)
 
   if (VIsual_active) {
     redraw_curbuf_later(UPD_INVERTED);  // update inverted part
-    update_screen(0);
+    update_screen();
   } else if (must_redraw) {
-    update_screen(0);
+    update_screen();
   } else if (redraw_cmdline || clear_cmdline || redraw_mode) {
     showmode();
   }
@@ -1841,7 +1841,7 @@ bool do_mouse(oparg_T *oap, int c, int dir, long count, bool fixindent)
       if (jump_flags) {
         jump_flags = jump_to_mouse(jump_flags, NULL, which_button);
         redraw_curbuf_later(VIsual_active ? UPD_INVERTED : UPD_VALID);
-        update_screen(0);
+        update_screen();
         setcursor();
         ui_flush();  // Update before showing popup menu
       }
diff --git a/src/nvim/ops.c b/src/nvim/ops.c
index dee23e9193..7fbf495922 100644
--- a/src/nvim/ops.c
+++ b/src/nvim/ops.c
@@ -2220,7 +2220,8 @@ void op_insert(oparg_T *oap, long count1)
 
   // vis block is still marked. Get rid of it now.
   curwin->w_cursor.lnum = oap->start.lnum;
-  update_screen(UPD_INVERTED);
+  redraw_curbuf_later(UPD_INVERTED);
+  update_screen();
 
   if (oap->motion_type == kMTBlockWise) {
     // When 'virtualedit' is used, need to insert the extra spaces before
@@ -2772,7 +2773,10 @@ static void op_yank_reg(oparg_T *oap, bool message, yankreg_T *reg, bool append)
       }
 
       // redisplay now, so message is not deleted
-      update_topline_redraw();
+      update_topline(curwin);
+      if (must_redraw) {
+        update_screen();
+      }
       if (yank_type == kMTBlockWise) {
         smsg(NGETTEXT("block of %" PRId64 " line yanked%s",
                       "block of %" PRId64 " lines yanked%s", yanklines),
diff --git a/src/nvim/option.c b/src/nvim/option.c
index e7d0b171f6..4a93fddc1b 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -147,6 +147,13 @@ typedef enum {
 # include "option.c.generated.h"
 #endif
 
+void set_init_tablocal(void)
+{
+  // susy baka: cmdheight calls itself OPT_GLOBAL but is really tablocal!
+  int ch_idx = findoption("cmdheight");
+  p_ch = (long)options[ch_idx].def_val;
+}
+
 /// Initialize the options, first part.
 ///
 /// Called only once from main(), just after creating the first buffer.
@@ -2634,9 +2641,8 @@ static char *set_num_option(int opt_idx, char_u *varp, long value, char *errbuf,
 /// Called after an option changed: check if something needs to be redrawn.
 void check_redraw(uint32_t flags)
 {
-  // Careful: P_RCLR and P_RALL are a combination of other P_ flags
-  bool doclear = (flags & P_RCLR) == P_RCLR;
-  bool all = ((flags & P_RALL) == P_RALL || doclear);
+  // Careful: P_RALL is a combination of other P_ flags
+  bool all = (flags & P_RALL) == P_RALL;
 
   if ((flags & P_RSTAT) || all) {  // mark all status lines and window bars dirty
     status_redraw_all();
@@ -2651,9 +2657,7 @@ void check_redraw(uint32_t flags)
   if (flags & P_RWINONLY) {
     redraw_later(curwin, UPD_NOT_VALID);
   }
-  if (doclear) {
-    redraw_all_later(UPD_CLEAR);
-  } else if (all) {
+  if (all) {
     redraw_all_later(UPD_NOT_VALID);
   }
 }
diff --git a/src/nvim/option_defs.h b/src/nvim/option_defs.h
index e27607d7a8..4e48c992c2 100644
--- a/src/nvim/option_defs.h
+++ b/src/nvim/option_defs.h
@@ -492,7 +492,7 @@ EXTERN unsigned dy_flags;
 #define DY_LASTLINE             0x001
 #define DY_TRUNCATE             0x002
 #define DY_UHEX                 0x004
-// code should use msg_use_msgsep() to check if msgsep is active
+// legacy flag, not used
 #define DY_MSGSEP               0x008
 EXTERN int p_ed;                // 'edcompatible'
 EXTERN char *p_ead;             // 'eadirection'
diff --git a/src/nvim/options.lua b/src/nvim/options.lua
index aa643eec36..82fd0d7428 100644
--- a/src/nvim/options.lua
+++ b/src/nvim/options.lua
@@ -20,7 +20,7 @@
 -- lists: (nil), comma, onecomma, flags, flagscomma
 -- scopes: global, buffer, window
 -- redraw options: statuslines, current_window, curent_window_only,
---                 current_buffer, all_windows, everything, curswant
+--                 current_buffer, all_windows, curswant
 -- defaults: {condition=#if condition, if_true=default, if_false=default}
 -- #if condition:
 --    string: #ifdef string
@@ -128,7 +128,6 @@ return {
       full_name='background', abbreviation='bg',
       short_desc=N_("\"dark\" or \"light\", used for highlight colors"),
       type='string', scope={'global'},
-      redraw={'all_windows'},
       varname='p_bg',
       defaults={if_true="dark"}
     },
@@ -395,7 +394,6 @@ return {
       short_desc=N_("number of columns in the display"),
       type='number', scope={'global'},
       no_mkrc=true,
-      redraw={'everything'},
       varname='p_columns',
       defaults={if_true=macros('DFLT_COLS')}
     },
@@ -422,7 +420,6 @@ return {
       full_name='compatible', abbreviation='cp',
       short_desc=N_("No description"),
       type='bool', scope={'global'},
-      redraw={'all_windows'},
       varname='p_force_off',
       -- pri_mkrc isn't needed here, optval_default()
       -- always returns TRUE for 'compatible'
@@ -663,7 +660,7 @@ return {
       deny_duplicates=true,
       redraw={'all_windows'},
       varname='p_dy',
-      defaults={if_true="lastline,msgsep"}
+      defaults={if_true="lastline"}
     },
     {
       full_name='eadirection', abbreviation='ead',
@@ -708,7 +705,6 @@ return {
       full_name='equalalways', abbreviation='ea',
       short_desc=N_("windows are automatically made the same size"),
       type='bool', scope={'global'},
-      redraw={'all_windows'},
       varname='p_ea',
       defaults={if_true=true}
     },
@@ -1051,7 +1047,6 @@ return {
       full_name='guioptions', abbreviation='go',
       short_desc=N_("GUI: Which components and options are used"),
       type='string', list='flags', scope={'global'},
-      redraw={'all_windows'},
       enable_if=false,
     },
     {
@@ -1195,7 +1190,6 @@ return {
       full_name='inccommand', abbreviation='icm',
       short_desc=N_("Live preview of substitution"),
       type='string', scope={'global'},
-      redraw={'all_windows'},
       varname='p_icm',
       defaults={if_true="nosplit"}
     },
@@ -1403,7 +1397,6 @@ return {
       short_desc=N_("of lines in the display"),
       type='number', scope={'global'},
       no_mkrc=true,
-      redraw={'everything'},
       varname='p_lines',
       defaults={if_true=macros('DFLT_ROWS')}
     },
@@ -2023,7 +2016,6 @@ return {
       full_name='scrolloff', abbreviation='so',
       short_desc=N_("minimum nr. of lines above and below cursor"),
       type='number', scope={'global', 'window'},
-      redraw={'all_windows'},
       varname='p_so',
       defaults={if_true=0}
     },
@@ -2260,7 +2252,6 @@ return {
       full_name='sidescrolloff', abbreviation='siso',
       short_desc=N_("min. nr. of columns to left and right of cursor"),
       type='number', scope={'global', 'window'},
-      redraw={'all_windows'},
       varname='p_siso',
       defaults={if_true=0}
     },
@@ -2453,7 +2444,7 @@ return {
       short_desc=N_("custom format for the console tab pages line"),
       type='string', scope={'global'},
       modelineexpr=true,
-      redraw={'all_windows'},
+      redraw={'statuslines'},
       varname='p_tal',
       defaults={if_true=""}
     },
diff --git a/src/nvim/popupmenu.c b/src/nvim/popupmenu.c
index 5483c9cb94..74376c8b8a 100644
--- a/src/nvim/popupmenu.c
+++ b/src/nvim/popupmenu.c
@@ -818,7 +818,7 @@ static bool pum_set_selected(int n, int repeat)
             // TODO(bfredl): can simplify, get rid of the flag munging?
             // or at least eliminate extra redraw before win_enter()?
             pum_is_visible = false;
-            update_screen(0);
+            update_screen();
             pum_is_visible = true;
 
             if (!resized && win_valid(curwin_save)) {
@@ -830,7 +830,7 @@ static bool pum_set_selected(int n, int repeat)
             // May need to update the screen again when there are
             // autocommands involved.
             pum_is_visible = false;
-            update_screen(0);
+            update_screen();
             pum_is_visible = true;
           }
         }
diff --git a/src/nvim/quickfix.c b/src/nvim/quickfix.c
index eeba7fe3c3..f9d139c466 100644
--- a/src/nvim/quickfix.c
+++ b/src/nvim/quickfix.c
@@ -2784,7 +2784,10 @@ static void qf_jump_print_msg(qf_info_T *qi, int qf_index, qfline_T *qf_ptr, buf
   // Update the screen before showing the message, unless the screen
   // scrolled up.
   if (!msg_scrolled) {
-    update_topline_redraw();
+    update_topline(curwin);
+    if (must_redraw) {
+      update_screen();
+    }
   }
   snprintf((char *)IObuff, IOSIZE, _("(%d of %d)%s%s: "), qf_index,
            qf_get_curlist(qi)->qf_count,
diff --git a/src/nvim/search.c b/src/nvim/search.c
index 336dd50292..ed0f25cba0 100644
--- a/src/nvim/search.c
+++ b/src/nvim/search.c
@@ -2321,7 +2321,7 @@ void showmatch(int c)
         dollar_vcol = -1;
       }
       curwin->w_virtcol++;              // do display ')' just before "$"
-      update_screen(UPD_VALID);         // show the new char first
+      update_screen();                  // show the new char first
 
       save_dollar_vcol = dollar_vcol;
       save_state = State;
diff --git a/src/nvim/state.c b/src/nvim/state.c
index 0353e61742..7712fcd39a 100644
--- a/src/nvim/state.c
+++ b/src/nvim/state.c
@@ -57,7 +57,7 @@ getkey:
       // Duplicate display updating logic in vgetorpeek()
       if (((State & MODE_INSERT) != 0 || p_lz) && (State & MODE_CMDLINE) == 0
           && must_redraw != 0 && !need_wait_return) {
-        update_screen(0);
+        update_screen();
         setcursor();  // put cursor back where it belongs
       }
       // Flush screen updates before blocking
diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index c52586fea2..e54a1c8334 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -522,7 +522,7 @@ static int terminal_check(VimState *state)
   terminal_check_cursor();
 
   if (must_redraw) {
-    update_screen(0);
+    update_screen();
   }
 
   if (need_maketitle) {  // Update title in terminal-mode. #7248
diff --git a/src/nvim/ui_compositor.c b/src/nvim/ui_compositor.c
index 8ef24b484e..47c83b8ed1 100644
--- a/src/nvim/ui_compositor.c
+++ b/src/nvim/ui_compositor.c
@@ -138,7 +138,7 @@ bool ui_comp_should_draw(void)
 ///
 /// TODO(bfredl): later on the compositor should just use win_float_pos events,
 /// though that will require slight event order adjustment: emit the win_pos
-/// events in the beginning of  update_screen(0), rather than in ui_flush()
+/// events in the beginning of update_screen(), rather than in ui_flush()
 bool ui_comp_put_grid(ScreenGrid *grid, int row, int col, int height, int width, bool valid,
                       bool on_top)
 {
diff --git a/src/nvim/version.c b/src/nvim/version.c
index 5888d4614e..d4d406482d 100644
--- a/src/nvim/version.c
+++ b/src/nvim/version.c
@@ -2324,6 +2324,7 @@ static void do_intro_line(long row, char *mesg, int attr)
 /// @param eap
 void ex_intro(exarg_T *eap)
 {
+  // TODO(bfredl): use msg_grid instead!
   screenclear();
   intro_message(true);
   wait_return(true);
diff --git a/src/nvim/window.c b/src/nvim/window.c
index c3806e10ff..c0edef7abc 100644
--- a/src/nvim/window.c
+++ b/src/nvim/window.c
@@ -3865,13 +3865,12 @@ void close_others(int message, int forceit)
 }
 
 // Allocate the first window and put an empty buffer in it.
-// Called from main().
-//
-// Return FAIL when something goes wrong.
-int win_alloc_first(void)
+// Only called from main().
+void win_alloc_first(void)
 {
   if (win_alloc_firstwin(NULL) == FAIL) {
-    return FAIL;
+    // allocating first buffer before any autocmds should not fail.
+    abort();
   }
 
   first_tabpage = alloc_tabpage();
@@ -3880,8 +3879,6 @@ int win_alloc_first(void)
   curtab->tp_firstwin = firstwin;
   curtab->tp_lastwin = lastwin;
   curtab->tp_curwin = curwin;
-
-  return OK;
 }
 
 // Init `aucmd_win`. This can only be done after the first window