Merge pull request #9530 from bfredl/pum_float

Implement popupmenu as a floating grid internally to reduce flicker

22 files changed, 710 insertions, 195 deletions

diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index 928d473b04..8abc43c2aa 100644
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -23,6 +23,7 @@ set(GENERATOR_DIR ${CMAKE_CURRENT_LIST_DIR}/generators)
 set(GENERATED_DIR ${PROJECT_BINARY_DIR}/src/nvim/auto)
 set(API_DISPATCH_GENERATOR ${GENERATOR_DIR}/gen_api_dispatch.lua)
 set(API_UI_EVENTS_GENERATOR ${GENERATOR_DIR}/gen_api_ui_events.lua)
+set(GENERATOR_C_GRAMMAR ${GENERATOR_DIR}/c_grammar.lua)
 set(API_METADATA ${PROJECT_BINARY_DIR}/api_metadata.mpack)
 set(FUNCS_DATA ${PROJECT_BINARY_DIR}/funcs_data.mpack)
 set(MSGPACK_LUA_C_BINDINGS ${GENERATED_DIR}/msgpack_lua_c_bindings.generated.c)
@@ -269,6 +270,7 @@ add_custom_command(
     ${API_HEADERS}
     ${MSGPACK_RPC_HEADERS}
     ${API_DISPATCH_GENERATOR}
+    ${GENERATOR_C_GRAMMAR}
     ${CMAKE_CURRENT_LIST_DIR}/api/dispatch_deprecated.lua
 )
 
@@ -300,6 +302,7 @@ add_custom_command(
                      ${GENERATED_UI_EVENTS_METADATA}
   DEPENDS
     ${API_UI_EVENTS_GENERATOR}
+    ${GENERATOR_C_GRAMMAR}
     ${CMAKE_CURRENT_LIST_DIR}/api/ui_events.in.h
 )
 
diff --git a/src/nvim/api/ui.c b/src/nvim/api/ui.c
index bc8a1a941f..b77516d588 100644
--- a/src/nvim/api/ui.c
+++ b/src/nvim/api/ui.c
@@ -113,6 +113,8 @@ void nvim_ui_attach(uint64_t channel_id, Integer width, Integer height,
   ui->set_title = remote_ui_set_title;
   ui->set_icon = remote_ui_set_icon;
   ui->option_set = remote_ui_option_set;
+  ui->win_scroll_over_start = remote_ui_win_scroll_over_start;
+  ui->win_scroll_over_reset = remote_ui_win_scroll_over_reset;
   ui->event = remote_ui_event;
   ui->inspect = remote_ui_inspect;
 
@@ -459,7 +461,7 @@ static void remote_ui_put(UI *ui, const char *cell)
 static void remote_ui_raw_line(UI *ui, Integer grid, Integer row,
                                Integer startcol, Integer endcol,
                                Integer clearcol, Integer clearattr,
-                               Boolean wrap, const schar_T *chunk,
+                               LineFlags flags, const schar_T *chunk,
                                const sattr_T *attrs)
 {
   UIData *data = ui->data;
diff --git a/src/nvim/api/ui_events.in.h b/src/nvim/api/ui_events.in.h
index 59a7780651..ef3ff0f4c2 100644
--- a/src/nvim/api/ui_events.in.h
+++ b/src/nvim/api/ui_events.in.h
@@ -38,6 +38,9 @@ void set_icon(String icon)
   FUNC_API_SINCE(3);
 void option_set(String name, Object value)
   FUNC_API_SINCE(4) FUNC_API_BRIDGE_IMPL;
+// Stop event is not exported as such, represented by EOF in the msgpack stream.
+void stop(void)
+  FUNC_API_NOEXPORT;
 
 // First revison of the grid protocol, used by default
 void update_fg(Integer fg)
@@ -71,28 +74,39 @@ void hl_attr_define(Integer id, HlAttrs rgb_attrs, HlAttrs cterm_attrs,
                     Array info)
   FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL FUNC_API_BRIDGE_IMPL;
 void grid_resize(Integer grid, Integer width, Integer height)
-  FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL;
+  FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL FUNC_API_COMPOSITOR_IMPL;
 void grid_clear(Integer grid)
-  FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL;
+  FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL FUNC_API_COMPOSITOR_IMPL;
 void grid_cursor_goto(Integer grid, Integer row, Integer col)
-  FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL;
+  FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL FUNC_API_COMPOSITOR_IMPL;
 void grid_line(Integer grid, Integer row, Integer col_start, Array data)
   FUNC_API_SINCE(5) FUNC_API_REMOTE_ONLY;
 void grid_scroll(Integer grid, Integer top, Integer bot,
                  Integer left, Integer right, Integer rows, Integer cols)
-  FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL;
+  FUNC_API_SINCE(5) FUNC_API_REMOTE_IMPL FUNC_API_COMPOSITOR_IMPL;
 void grid_destroy(Integer grid)
   FUNC_API_SINCE(6) FUNC_API_REMOTE_ONLY;
 
+// For perfomance and simplicity, we use the dense screen representation
+// in internal code, such as compositor and TUI. The remote_ui module will
+// translate this in to the public grid_line format.
+void raw_line(Integer grid, Integer row, Integer startcol,
+              Integer endcol, Integer clearcol, Integer clearattr,
+              LineFlags flags, const schar_T *chunk, const sattr_T *attrs)
+  FUNC_API_NOEXPORT FUNC_API_COMPOSITOR_IMPL;
+
+void event(char *name, Array args, bool *args_consumed)
+  FUNC_API_NOEXPORT;
+
 void win_pos(Integer grid, Integer win, Integer startrow,
              Integer startcol, Integer width, Integer height)
   FUNC_API_SINCE(6) FUNC_API_REMOTE_ONLY;
 void win_hide(Integer grid)
   FUNC_API_SINCE(6) FUNC_API_REMOTE_ONLY;
 void win_scroll_over_start(void)
-  FUNC_API_SINCE(6) FUNC_API_REMOTE_ONLY;
+  FUNC_API_SINCE(6) FUNC_API_BRIDGE_IMPL FUNC_API_COMPOSITOR_IMPL;
 void win_scroll_over_reset(void)
-  FUNC_API_SINCE(6) FUNC_API_REMOTE_ONLY;
+  FUNC_API_SINCE(6) FUNC_API_BRIDGE_IMPL FUNC_API_COMPOSITOR_IMPL;
 
 void popupmenu_show(Array items, Integer selected,
                     Integer row, Integer col, Integer grid)
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index bb16e2ae4d..a63dd97ba8 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -473,6 +473,8 @@ static void insert_enter(InsertState *s)
     o_lnum = curwin->w_cursor.lnum;
   }
 
+  pum_check_clear();
+
   foldUpdateAfterInsert();
   // When CTRL-C was typed got_int will be set, with the result
   // that the autocommands won't be executed. When mapped got_int
@@ -1447,6 +1449,7 @@ ins_redraw (
     redrawWinline(curwin, curwin->w_cursor.lnum);
   }
 
+  pum_check_clear();
   if (must_redraw) {
     update_screen(0);
   } else if (clear_cmdline || redraw_cmdline) {
@@ -2490,20 +2493,10 @@ void set_completion(colnr_T startcol, list_T *list)
 static pumitem_T *compl_match_array = NULL;
 static int compl_match_arraysize;
 
+
 /*
  * Update the screen and when there is any scrolling remove the popup menu.
  */
-static void ins_compl_upd_pum(void)
-{
-  int h;
-
-  if (compl_match_array != NULL) {
-    h = curwin->w_cline_height;
-    update_screen(0);
-    if (h != curwin->w_cline_height)
-      ins_compl_del_pum();
-  }
-}
 
 /*
  * Remove any popup menu.
@@ -2511,7 +2504,7 @@ static void ins_compl_upd_pum(void)
 static void ins_compl_del_pum(void)
 {
   if (compl_match_array != NULL) {
-    pum_undisplay();
+    pum_undisplay(false);
     xfree(compl_match_array);
     compl_match_array = NULL;
   }
@@ -4305,17 +4298,14 @@ ins_compl_next (
   }
 
   if (!allow_get_expansion) {
-    /* may undisplay the popup menu first */
-    ins_compl_upd_pum();
-
-    /* redraw to show the user what was inserted */
+    // redraw to show the user what was inserted
     update_screen(0);
 
-    /* display the updated popup menu */
+    // display the updated popup menu
     ins_compl_show_pum();
 
-    /* Delete old text to be replaced, since we're still searching and
-     * don't want to match ourselves!  */
+    // Delete old text to be replaced, since we're still searching and
+    // don't want to match ourselves!
     ins_compl_delete();
   }
 
@@ -4862,8 +4852,6 @@ static int ins_complete(int c, bool enable_pum)
   save_w_leftcol = curwin->w_leftcol;
   n = ins_compl_next(true, ins_compl_key2count(c), insert_match, false);
 
-  /* may undisplay the popup menu */
-  ins_compl_upd_pum();
 
   if (n > 1)            /* all matches have been found */
     compl_matches = n;
@@ -7144,11 +7132,17 @@ static void ins_reg(void)
    * message for it. Only call it explicitly. */
   ++no_u_sync;
   if (regname == '=') {
-    /* Sync undo when evaluating the expression calls setline() or
-     * append(), so that it can be undone separately. */
+    pos_T curpos = curwin->w_cursor;
+
+    // Sync undo when evaluating the expression calls setline() or
+    // append(), so that it can be undone separately.
     u_sync_once = 2;
 
     regname = get_expr_register();
+
+    // Cursor may be moved back a column.
+    curwin->w_cursor = curpos;
+    check_cursor();
   }
   if (regname == NUL || !valid_yank_reg(regname, false)) {
     vim_beep(BO_REG);
@@ -7939,7 +7933,6 @@ static void ins_mouse(int c)
 static void ins_mousescroll(int dir)
 {
   win_T *const old_curwin = curwin;
-  bool did_scroll = false;
   pos_T tpos = curwin->w_cursor;
 
   if (mouse_row >= 0 && mouse_col >= 0) {
@@ -7969,7 +7962,6 @@ static void ins_mousescroll(int dir)
     } else {
         mouse_scroll_horiz(dir);
     }
-    did_scroll = true;
   }
 
   curwin->w_redr_status = TRUE;
@@ -7977,14 +7969,6 @@ static void ins_mousescroll(int dir)
   curwin = old_curwin;
   curbuf = curwin->w_buffer;
 
-  /* The popup menu may overlay the window, need to redraw it.
-   * TODO: Would be more efficient to only redraw the windows that are
-   * overlapped by the popup menu. */
-  if (pum_visible() && did_scroll) {
-    redraw_all_later(NOT_VALID);
-    ins_compl_show_pum();
-  }
-
   if (!equalpos(curwin->w_cursor, tpos)) {
     start_arrow(&tpos);
     can_cindent = true;
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 786769dc7d..bd03160bcd 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -51,6 +51,7 @@
 #include "nvim/option.h"
 #include "nvim/os_unix.h"
 #include "nvim/path.h"
+#include "nvim/popupmnu.h"
 #include "nvim/regexp.h"
 #include "nvim/screen.h"
 #include "nvim/search.h"
@@ -6051,7 +6052,12 @@ static int open_cmdwin(void)
 
   /* Don't execute autocommands while creating the window. */
   block_autocmds();
-  /* don't use a new tab page */
+
+  // When using completion in Insert mode with <C-R>=<C-F> one can open the
+  // command line window, but we don't want the popup menu then.
+  pum_undisplay(true);
+
+  // don't use a new tab page
   cmdmod.tab = 0;
   cmdmod.noswapfile = 1;
 
diff --git a/src/nvim/generators/c_grammar.lua b/src/nvim/generators/c_grammar.lua
index d3047e1a9c..40bdc3e30c 100644
--- a/src/nvim/generators/c_grammar.lua
+++ b/src/nvim/generators/c_grammar.lua
@@ -25,6 +25,7 @@ local c_id = (
 local c_void = P('void')
 local c_param_type = (
   ((P('Error') * fill * P('*') * fill) * Cc('error')) +
+  C((P('const ') ^ -1) * (c_id) * (ws ^ 1) * P('*')) +
   (C(c_id) * (ws ^ 1))
   )
 local c_type = (C(c_void) * (ws ^ 1)) + c_param_type
@@ -43,6 +44,7 @@ local c_proto = Ct(
   (fill * Cg((P('FUNC_API_REMOTE_ONLY') * Cc(true)), 'remote_only') ^ -1) *
   (fill * Cg((P('FUNC_API_REMOTE_IMPL') * Cc(true)), 'remote_impl') ^ -1) *
   (fill * Cg((P('FUNC_API_BRIDGE_IMPL') * Cc(true)), 'bridge_impl') ^ -1) *
+  (fill * Cg((P('FUNC_API_COMPOSITOR_IMPL') * Cc(true)), 'compositor_impl') ^ -1) *
   fill * P(';')
   )
 
diff --git a/src/nvim/generators/gen_api_ui_events.lua b/src/nvim/generators/gen_api_ui_events.lua
index e76b601d8a..c8ab310b02 100644
--- a/src/nvim/generators/gen_api_ui_events.lua
+++ b/src/nvim/generators/gen_api_ui_events.lua
@@ -54,7 +54,7 @@ for i = 1, #events do
   ev = events[i]
   assert(ev.return_type == 'void')
 
-  if ev.since == nil then
+  if ev.since == nil and not ev.noexport then
     print("Ui event "..ev.name.." lacks since field.\n")
     os.exit(1)
   end
@@ -65,7 +65,7 @@ for i = 1, #events do
     write_signature(proto_output, ev, 'UI *ui')
     proto_output:write(';\n')
 
-    if not ev.remote_impl then
+    if not ev.remote_impl and not ev.noexport then
       remote_output:write('static void remote_ui_'..ev.name)
       write_signature(remote_output, ev, 'UI *ui')
       remote_output:write('\n{\n')
@@ -74,8 +74,7 @@ for i = 1, #events do
       remote_output:write('}\n\n')
     end
 
-    if not ev.bridge_impl then
-
+    if not ev.bridge_impl and not ev.noexport then
       send, argv, recv, recv_argv, recv_cleanup = '', '', '', '', ''
       argc = 1
       for j = 1, #ev.parameters do
@@ -138,21 +137,36 @@ for i = 1, #events do
     call_output:write('\n{\n')
     if ev.remote_only then
       write_arglist(call_output, ev, false)
-      call_output:write('  UI_LOG('..ev.name..', 0);\n')
+      call_output:write('  UI_LOG('..ev.name..');\n')
       call_output:write('  ui_event("'..ev.name..'", args);\n')
+    elseif ev.compositor_impl then
+      call_output:write('  UI_CALL')
+      write_signature(call_output, ev, '!ui->composed, '..ev.name..', ui', true)
+      call_output:write(";\n")
     else
       call_output:write('  UI_CALL')
-      write_signature(call_output, ev, ev.name, true)
+      write_signature(call_output, ev, 'true, '..ev.name..', ui', true)
       call_output:write(";\n")
     end
     call_output:write("}\n\n")
   end
 
+  if ev.compositor_impl then
+    call_output:write('void ui_composed_call_'..ev.name)
+    write_signature(call_output, ev, '')
+    call_output:write('\n{\n')
+    call_output:write('  UI_CALL')
+    write_signature(call_output, ev, 'ui->composed, '..ev.name..', ui', true)
+    call_output:write(";\n")
+    call_output:write("}\n\n")
+  end
+
 end
 
 proto_output:close()
 call_output:close()
 remote_output:close()
+bridge_output:close()
 
 -- don't expose internal attributes like "impl_name" in public metadata
 exported_attributes = {'name', 'parameters',
@@ -168,7 +182,9 @@ for _,ev in ipairs(events) do
       p[1] = 'Dictionary'
     end
   end
-  exported_events[#exported_events+1] = ev_exported
+  if not ev.noexport then
+    exported_events[#exported_events+1] = ev_exported
+  end
 end
 
 packed = mpack.pack(exported_events)
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index ccdf8f87ab..f47697b190 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -194,12 +194,15 @@ EXTERN int compl_cont_status INIT(= 0);
 EXTERN int cmdmsg_rl INIT(= false);  // cmdline is drawn right to left
 EXTERN int msg_col;
 EXTERN int msg_row;
-EXTERN int msg_scrolled;        /* Number of screen lines that windows have
-                                * scrolled because of printing messages. */
-EXTERN int msg_scrolled_ign INIT(= FALSE);
-/* when TRUE don't set need_wait_return in
-   msg_puts_attr() when msg_scrolled is
-   non-zero */
+EXTERN int msg_scrolled;        // Number of screen lines that windows have
+                                // scrolled because of printing messages.
+// when true don't set need_wait_return in msg_puts_attr()
+// when msg_scrolled is non-zero
+EXTERN bool msg_scrolled_ign INIT(= false);
+// Whether the screen is damaged due to scrolling. Sometimes msg_scrolled
+// is reset before the screen is redrawn, so we need to keep track of this.
+EXTERN bool msg_did_scroll INIT(= false);
+
 
 EXTERN char_u   *keep_msg INIT(= NULL);     /* msg to be shown after redraw */
 EXTERN int keep_msg_attr INIT(= 0);         /* highlight attr for keep_msg */
diff --git a/src/nvim/grid_defs.h b/src/nvim/grid_defs.h
index cf9e550f48..d9ccdbbdab 100644
--- a/src/nvim/grid_defs.h
+++ b/src/nvim/grid_defs.h
@@ -1,6 +1,8 @@
 #ifndef NVIM_GRID_DEFS_H
 #define NVIM_GRID_DEFS_H
 
+#include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
 
 #include "nvim/types.h"
@@ -48,8 +50,15 @@ typedef struct {
   // offsets for the grid relative to the global screen
   int row_offset;
   int col_offset;
+
+  // state owned by the compositor.
+  int comp_row;
+  int comp_col;
+  size_t comp_index;
+  bool comp_disabled;
 } ScreenGrid;
 
-#define SCREEN_GRID_INIT { 0, NULL, NULL, NULL, NULL, 0, 0, 0, 0 }
+#define SCREEN_GRID_INIT { 0, NULL, NULL, NULL, NULL, 0, 0, 0, 0, 0, 0, 0, \
+                           false }
 
 #endif  // NVIM_GRID_DEFS_H
diff --git a/src/nvim/highlight.c b/src/nvim/highlight.c
index 41d60fa3ea..20cdbc7ec9 100644
--- a/src/nvim/highlight.c
+++ b/src/nvim/highlight.c
@@ -101,6 +101,9 @@ static int get_attr_entry(HlEntry entry)
 /// When a UI connects, we need to send it the table of highlights used so far.
 void ui_send_all_hls(UI *ui)
 {
+  if (!ui->hl_attr_define) {
+    return;
+  }
   for (size_t i = 1; i < kv_size(attr_entries); i++) {
     Array inspect = hl_inspect((int)i);
     ui->hl_attr_define(ui, (Integer)i, kv_A(attr_entries, i).attr,
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 17f3a894d4..9c8711495c 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -154,6 +154,7 @@ void event_init(void)
   remote_ui_init();
   api_vim_init();
   terminal_init();
+  ui_init();
 }
 
 /// @returns false if main_loop could not be closed gracefully
diff --git a/src/nvim/memline.c b/src/nvim/memline.c
index 4c4f7d65bd..662eda3c7c 100644
--- a/src/nvim/memline.c
+++ b/src/nvim/memline.c
@@ -3412,7 +3412,9 @@ static char *findswapname(buf_T *buf, char **dirp, char *old_fname,
 # endif
             xfree(name);
 
-            /* pretend screen didn't scroll, need redraw anyway */
+            // pretend screen didn't scroll, need redraw anyway
+            // TODO(bfredl): when doing the message grid refactor,
+            // simplify this special case.
             msg_scrolled = 0;
             redraw_all_later(NOT_VALID);
           }
diff --git a/src/nvim/message.c b/src/nvim/message.c
index 1330460867..4552999256 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -1960,8 +1960,9 @@ int msg_scrollsize(void)
  */
 static void msg_scroll_up(void)
 {
-  if (msg_scrolled == 0) {
+  if (!msg_did_scroll) {
     ui_call_win_scroll_over_start();
+    msg_did_scroll = true;
   }
   if (dy_flags & DY_MSGSEP) {
     if (msg_scrolled == 0) {
diff --git a/src/nvim/os_unix.c b/src/nvim/os_unix.c
index 09ba718302..351350d939 100644
--- a/src/nvim/os_unix.c
+++ b/src/nvim/os_unix.c
@@ -139,7 +139,7 @@ void mch_exit(int r)
   exiting = true;
 
   ui_flush();
-  ui_builtin_stop();
+  ui_call_stop();
   ml_close_all(true);           // remove all memfiles
 
   if (!event_teardown() && r == 0) {
diff --git a/src/nvim/popupmnu.c b/src/nvim/popupmnu.c
index 056770f2c0..d64406846a 100644
--- a/src/nvim/popupmnu.c
+++ b/src/nvim/popupmnu.c
@@ -19,6 +19,7 @@
 #include "nvim/move.h"
 #include "nvim/option.h"
 #include "nvim/screen.h"
+#include "nvim/ui_compositor.h"
 #include "nvim/search.h"
 #include "nvim/strings.h"
 #include "nvim/memory.h"
@@ -41,8 +42,11 @@ static int pum_row;                 // top row of pum
 static int pum_col;                 // left column of pum
 
 static bool pum_is_visible = false;
+static bool pum_is_drawn = false;
 static bool pum_external = false;
 
+static ScreenGrid pum_grid = SCREEN_GRID_INIT;
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "popupmnu.c.generated.h"
 #endif
@@ -85,6 +89,7 @@ void pum_display(pumitem_T *array, int size, int selected, bool array_changed)
     // Mark the pum as visible already here,
     // to avoid that must_redraw is set when 'cursorcolumn' is on.
     pum_is_visible = true;
+    pum_is_drawn = true;
     validate_cursor_col();
     above_row = 0;
     below_row = cmdline_row;
@@ -317,7 +322,7 @@ void pum_display(pumitem_T *array, int size, int selected, bool array_changed)
 /// Redraw the popup menu, using "pum_first" and "pum_selected".
 void pum_redraw(void)
 {
-  int row = pum_row;
+  int row = 0;
   int col;
   int attr_norm = win_hl_attr(curwin, HLF_PNI);
   int attr_select = win_hl_attr(curwin, HLF_PSI);
@@ -334,6 +339,37 @@ void pum_redraw(void)
   int round;
   int n;
 
+  int grid_width = pum_width;
+  int col_off = 0;
+  bool extra_space = false;
+  if (curwin->w_p_rl) {
+    col_off = pum_width;
+    if (pum_col < curwin->w_wincol + curwin->w_width - 1) {
+      grid_width += 1;
+      extra_space = true;
+    }
+  } else if (pum_col > 0) {
+    grid_width += 1;
+    col_off = 1;
+    extra_space = true;
+  }
+  if (pum_scrollbar > 0) {
+    grid_width++;
+  }
+
+  grid_assign_handle(&pum_grid);
+  bool moved = ui_comp_put_grid(&pum_grid, pum_row, pum_col-col_off,
+                                pum_height, grid_width);
+
+  if (!pum_grid.chars
+      || pum_grid.Rows != pum_height || pum_grid.Columns != grid_width) {
+    grid_alloc(&pum_grid, pum_height, grid_width, !moved, false);
+    ui_call_grid_resize(pum_grid.handle, pum_grid.Columns, pum_grid.Rows);
+  } else if (moved) {
+    grid_invalidate(&pum_grid);
+  }
+
+
   // Never display more than we have
   if (pum_first > pum_size - pum_height) {
     pum_first = pum_size - pum_height;
@@ -356,17 +392,17 @@ void pum_redraw(void)
     screen_puts_line_start(row);
 
     // prepend a space if there is room
-    if (curwin->w_p_rl) {
-      if (pum_col < curwin->w_wincol + curwin->w_width - 1) {
-        grid_putchar(&default_grid, ' ', row, pum_col + 1, attr);
+    if (extra_space) {
+      if (curwin->w_p_rl) {
+        grid_putchar(&pum_grid, ' ', row, col_off + 1, attr);
+      } else {
+        grid_putchar(&pum_grid, ' ', row, col_off - 1, attr);
       }
-    } else if (pum_col > 0) {
-      grid_putchar(&default_grid, ' ', row, pum_col - 1, attr);
     }
 
     // Display each entry, use two spaces for a Tab.
     // Do this 3 times: For the main text, kind and extra info
-    col = pum_col;
+    col = col_off;
     totwidth = 0;
 
     for (round = 1; round <= 3; ++round) {
@@ -423,13 +459,13 @@ void pum_redraw(void)
                   size++;
                 }
               }
-              grid_puts_len(&default_grid, rt, (int)STRLEN(rt), row,
+              grid_puts_len(&pum_grid, rt, (int)STRLEN(rt), row,
                             col - size + 1, attr);
               xfree(rt_start);
               xfree(st);
               col -= width;
             } else {
-              grid_puts_len(&default_grid, st, (int)STRLEN(st), row, col, attr);
+              grid_puts_len(&pum_grid, st, (int)STRLEN(st), row, col, attr);
               xfree(st);
               col += width;
             }
@@ -440,11 +476,11 @@ void pum_redraw(void)
 
             // Display two spaces for a Tab.
             if (curwin->w_p_rl) {
-              grid_puts_len(&default_grid, (char_u *)"  ", 2, row, col - 1,
+              grid_puts_len(&pum_grid, (char_u *)"  ", 2, row, col - 1,
                             attr);
               col -= 2;
             } else {
-              grid_puts_len(&default_grid, (char_u *)"  ", 2, row, col, attr);
+              grid_puts_len(&pum_grid, (char_u *)"  ", 2, row, col, attr);
               col += 2;
             }
             totwidth += 2;
@@ -475,37 +511,37 @@ void pum_redraw(void)
       }
 
       if (curwin->w_p_rl) {
-        grid_fill(&default_grid, row, row + 1, pum_col - pum_base_width - n + 1,
+        grid_fill(&pum_grid, row, row + 1, col_off - pum_base_width - n + 1,
                   col + 1, ' ', ' ', attr);
-        col = pum_col - pum_base_width - n + 1;
+        col = col_off - pum_base_width - n + 1;
       } else {
-        grid_fill(&default_grid, row, row + 1, col,
-                  pum_col + pum_base_width + n, ' ', ' ', attr);
-        col = pum_col + pum_base_width + n;
+        grid_fill(&pum_grid, row, row + 1, col,
+                  col_off + pum_base_width + n, ' ', ' ', attr);
+        col = pum_base_width + n;
       }
       totwidth = pum_base_width + n;
     }
 
     if (curwin->w_p_rl) {
-      grid_fill(&default_grid, row, row + 1, pum_col - pum_width + 1, col + 1,
+      grid_fill(&pum_grid, row, row + 1, col_off - pum_width + 1, col + 1,
                 ' ', ' ', attr);
     } else {
-      grid_fill(&default_grid, row, row + 1, col, pum_col + pum_width, ' ', ' ',
+      grid_fill(&pum_grid, row, row + 1, col, col_off + pum_width, ' ', ' ',
                 attr);
     }
 
     if (pum_scrollbar > 0) {
       if (curwin->w_p_rl) {
-        grid_putchar(&default_grid, ' ', row, pum_col - pum_width,
+        grid_putchar(&pum_grid, ' ', row, col_off - pum_width,
                      i >= thumb_pos && i < thumb_pos + thumb_heigth
                      ? attr_thumb : attr_scroll);
       } else {
-        grid_putchar(&default_grid, ' ', row, pum_col + pum_width,
+        grid_putchar(&pum_grid, ' ', row, col_off + pum_width,
                      i >= thumb_pos && i < thumb_pos + thumb_heigth
                      ? attr_thumb : attr_scroll);
       }
     }
-    grid_puts_line_flush(&default_grid, false);
+    grid_puts_line_flush(&pum_grid, false);
     row++;
   }
 }
@@ -696,6 +732,8 @@ static int pum_set_selected(int n, int repeat)
 
             // Update the screen before drawing the popup menu.
             // Enable updating the status lines.
+            // 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);
             pum_is_visible = true;
@@ -725,17 +763,27 @@ static int pum_set_selected(int n, int repeat)
 }
 
 /// Undisplay the popup menu (later).
-void pum_undisplay(void)
+void pum_undisplay(bool immediate)
 {
   pum_is_visible = false;
   pum_array = NULL;
 
-  if (pum_external) {
-    ui_call_popupmenu_hide();
-  } else {
-    redraw_all_later(SOME_VALID);
-    redraw_tabline = true;
-    status_redraw_all();
+  if (immediate) {
+    pum_check_clear();
+  }
+}
+
+void pum_check_clear(void)
+{
+  if (!pum_is_visible && pum_is_drawn) {
+    if (pum_external) {
+      ui_call_popupmenu_hide();
+    } else {
+      ui_comp_remove_grid(&pum_grid);
+      // TODO(bfredl): consider keeping float grids allocated.
+      grid_free(&pum_grid);
+    }
+    pum_is_drawn = false;
   }
 }
 
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 2038fb4d2c..759eefaecc 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -110,6 +110,7 @@
 #include "nvim/syntax.h"
 #include "nvim/terminal.h"
 #include "nvim/ui.h"
+#include "nvim/ui_compositor.h"
 #include "nvim/undo.h"
 #include "nvim/version.h"
 #include "nvim/window.h"
@@ -153,6 +154,8 @@ static bool highlights_invalid = false;
 
 static bool conceal_cursor_used = false;
 
+static bool floats_invalid = false;
+
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "screen.c.generated.h"
 #endif
@@ -304,11 +307,15 @@ void update_screen(int type)
   ++display_tick;           /* let syntax code know we're in a next round of
                              * display updating */
 
-  /*
-   * if the screen was scrolled up when displaying a message, scroll it down
-   */
-  if (msg_scrolled) {
+  // Tricky: vim code can reset msg_scrolled behind our back, so need
+  // separate bookkeeping for now.
+  if (msg_did_scroll) {
     ui_call_win_scroll_over_reset();
+    msg_did_scroll = false;
+  }
+
+  // if the screen was scrolled up when displaying a message, scroll it down
+  if (msg_scrolled) {
     clear_cmdline = true;
     if (dy_flags & DY_MSGSEP) {
       int valid = MAX(Rows - msg_scrollsize(), 0);
@@ -453,17 +460,20 @@ void update_screen(int type)
 
     /* redraw status line after the window to minimize cursor movement */
     if (wp->w_redr_status) {
-      win_redr_status(wp, true);  // any popup menu will be redrawn below
+      win_redr_status(wp);
     }
   }
-  send_grid_resize = false;
-  highlights_invalid = false;
+
   end_search_hl();
   // May need to redraw the popup menu.
-  if (pum_drawn()) {
+  if (pum_drawn() && floats_invalid) {
     pum_redraw();
   }
 
+  send_grid_resize = false;
+  highlights_invalid = false;
+  floats_invalid = false;
+
   /* Reset b_mod_set flags.  Going through all windows is probably faster
    * than going through all buffers (there could be many buffers). */
   FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
@@ -4287,7 +4297,7 @@ win_line (
 /// screen positions.
 static void screen_adjust_grid(ScreenGrid **grid, int *row_off, int *col_off)
 {
-  if (!ui_is_external(kUIMultigrid) && *grid != &default_grid) {
+  if (!(*grid)->chars && *grid != &default_grid) {
     *row_off += (*grid)->row_offset;
     *col_off += (*grid)->col_offset;
     *grid = &default_grid;
@@ -4537,7 +4547,7 @@ void redraw_statuslines(void)
 {
   FOR_ALL_WINDOWS_IN_TAB(wp, curtab) {
     if (wp->w_redr_status) {
-      win_redr_status(wp, false);
+      win_redr_status(wp);
     }
   }
   if (redraw_tabline)
@@ -4808,7 +4818,7 @@ win_redr_status_matches (
 /// If inversion is possible we use it. Else '=' characters are used.
 /// If "ignore_pum" is true, also redraw statusline when the popup menu is
 /// displayed.
-static void win_redr_status(win_T *wp, int ignore_pum)
+static void win_redr_status(win_T *wp)
 {
   int row;
   char_u      *p;
@@ -4831,7 +4841,7 @@ static void win_redr_status(win_T *wp, int ignore_pum)
   if (wp->w_status_height == 0) {
     // no status line, can only be last window
     redraw_cmdline = true;
-  } else if (!redrawing() || (!ignore_pum && pum_drawn())) {