Merge pull request #1657 from tarruda/abstract-ui-fixes

[WIP] "abstract_ui" fixes and improvements

14 files changed, 225 insertions, 144 deletions

diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index e1a1fb18fa..89696410c9 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -2294,8 +2294,7 @@ static int pum_wanted(void)
     return FALSE;
 
   /* The display looks bad on a B&W display. */
-  if (t_colors < 8
-      )
+  if (!abstract_ui && t_colors < 8)
     return FALSE;
   return TRUE;
 }
diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index d60ce2de73..1dba3cd1e5 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -14440,7 +14440,7 @@ static void f_synIDattr(typval_T *argvars, typval_T *rettv)
     if (modec != 't' && modec != 'c' && modec != 'g')
       modec = 0;        /* replace invalid with current */
   } else {
-    if (t_colors > 1)
+    if (abstract_ui || t_colors > 1)
       modec = 'c';
     else
       modec = 't';
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 3661a65b11..b794ced428 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -71,6 +71,7 @@
 #include "nvim/os/time.h"
 #include "nvim/ex_cmds_defs.h"
 #include "nvim/mouse.h"
+#include "nvim/msgpack_rpc/channel.h"
 
 static int quitmore = 0;
 static int ex_pressedreturn = FALSE;
@@ -5398,10 +5399,16 @@ static void ex_stop(exarg_T *eap)
   /*
    * Disallow suspending for "rvim".
    */
-  if (!check_restricted()
-      ) {
-    if (!eap->forceit)
+  if (!check_restricted()) {
+    if (!eap->forceit) {
       autowrite_all();
+    }
+
+    if (abstract_ui) {
+      channel_close(last_message_source);
+      return;
+    }
+
     windgoto((int)Rows - 1, 0);
     out_char('\n');
     out_flush();
diff --git a/src/nvim/globals.h b/src/nvim/globals.h
index 11a7e9ecac..854dd33552 100644
--- a/src/nvim/globals.h
+++ b/src/nvim/globals.h
@@ -1245,6 +1245,9 @@ EXTERN int curr_tmode INIT(= TMODE_COOK); /* contains current terminal mode */
 EXTERN bool embedded_mode INIT(= false);
 // Using the "abstract_ui" termcap
 EXTERN bool abstract_ui INIT(= false);
+// Id of the last channel sent a message to nvim. Used to determine the target
+// of channel-specific actions such as suspending
+EXTERN uint64_t last_message_source INIT(= 0);
 
 /// Used to track the status of external functions.
 /// Currently only used for iconv().
diff --git a/src/nvim/main.c b/src/nvim/main.c
index 1f6c8ddc81..5e9fde67f5 100644
--- a/src/nvim/main.c
+++ b/src/nvim/main.c
@@ -281,9 +281,7 @@ int main(int argc, char **argv)
 
   event_init();
 
-  if (abstract_ui) {
-    t_colors = 256;
-  } else {
+  if (!abstract_ui) {
     // Print a warning if stdout is not a terminal TODO(tarruda): Remove this
     // check once the new terminal UI is implemented
     check_tty(&params);
diff --git a/src/nvim/msgpack_rpc/channel.c b/src/nvim/msgpack_rpc/channel.c
index 4c35cce09a..f2db65c605 100644
--- a/src/nvim/msgpack_rpc/channel.c
+++ b/src/nvim/msgpack_rpc/channel.c
@@ -45,6 +45,7 @@ typedef struct {
 
 typedef struct {
   uint64_t id;
+  size_t pending_requests;
   PMap(cstr_t) *subscribed_events;
   bool is_job, closed;
   msgpack_unpacker *unpacker;
@@ -83,7 +84,6 @@ static uint64_t next_id = 1;
 static PMap(uint64_t) *channels = NULL;
 static PMap(cstr_t) *event_strings = NULL;
 static msgpack_sbuffer out_buffer;
-static size_t pending_requests = 0;
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "msgpack_rpc/channel.c.generated.h"
@@ -103,14 +103,7 @@ void channel_init(void)
   }
 
   if (abstract_ui) {
-    // Add handler for "attach_ui"
     remote_ui_init();
-    String method = cstr_as_string("attach_ui");
-    MsgpackRpcRequestHandler handler = {.fn = remote_ui_attach, .defer = true};
-    msgpack_rpc_add_method_handler(method, handler);
-    method = cstr_as_string("detach_ui");
-    handler.fn = remote_ui_detach;
-    msgpack_rpc_add_method_handler(method, handler);
   }
 }
 
@@ -200,20 +193,21 @@ bool channel_send_event(uint64_t id, char *name, Array args)
     return false;
   }
 
-  if (pending_requests) {
-    DelayedNotification p = {
-      .channel = channel,
-      .method = cstr_to_string(name),
-      .args = args
-    };
-    // Pending request, queue the notification for sending later
-    *kl_pushp(DelayedNotification, delayed_notifications) = p;
-  } else {
-    if (channel) {
-      send_event(channel, name, args);
+  if (channel) {
+    if (channel->pending_requests) {
+      DelayedNotification p = {
+        .channel = channel,
+        .method = cstr_to_string(name),
+        .args = args
+      };
+      // Pending request, queue the notification for sending later
+      *kl_pushp(DelayedNotification, delayed_notifications) = p;
     } else {
-      broadcast_event(name, args);
+      send_event(channel, name, args);
     }
+  }  else {
+    // TODO(tarruda): Implement event broadcasting in vimscript
+    broadcast_event(name, args);
   }
 
   return true;
@@ -246,10 +240,10 @@ Object channel_send_call(uint64_t id,
   // Push the frame
   ChannelCallFrame frame = {request_id, false, false, NIL};
   kv_push(ChannelCallFrame *, channel->call_stack, &frame);
-  pending_requests++;
+  channel->pending_requests++;
   event_poll_until(-1, frame.returned);
   (void)kv_pop(channel->call_stack);
-  pending_requests--;
+  channel->pending_requests--;
 
   if (frame.errored) {
     api_set_error(err, Exception, "%s", frame.result.data.string.data);
@@ -261,7 +255,7 @@ Object channel_send_call(uint64_t id,
     free_channel(channel);
   }
 
-  if (!pending_requests) {
+  if (!channel->pending_requests) {
     send_delayed_notifications();
   }
 
@@ -492,6 +486,7 @@ static void on_request_event(Event event)
 {
   RequestEvent *e = event.data;
   Channel *channel = e->channel;
+  last_message_source = channel->id;
   MsgpackRpcRequestHandler handler = e->handler;
   Array args = e->args;
   uint64_t request_id = e->request_id;
@@ -644,6 +639,7 @@ static void close_channel(Channel *channel)
     uv_handle_t *handle = (uv_handle_t *)channel->data.streams.uv;
     if (handle) {
       uv_close(handle, close_cb);
+      free_channel(channel);
     } else {
       event_push((Event) { .handler = on_stdio_close }, false);
     }
@@ -687,6 +683,7 @@ static Channel *register_channel(void)
   rv->closed = false;
   rv->unpacker = msgpack_unpacker_new(MSGPACK_UNPACKER_INIT_BUFFER_SIZE);
   rv->id = next_id++;
+  rv->pending_requests = 0;
   rv->subscribed_events = pmap_new(cstr_t)();
   rv->next_request_id = 1;
   kv_init(rv->call_stack);
diff --git a/src/nvim/msgpack_rpc/remote_ui.c b/src/nvim/msgpack_rpc/remote_ui.c
index f980a77b4c..4db9c71ebb 100644
--- a/src/nvim/msgpack_rpc/remote_ui.c
+++ b/src/nvim/msgpack_rpc/remote_ui.c
@@ -26,18 +26,44 @@ static PMap(uint64_t) *connected_uis = NULL;
 void remote_ui_init(void)
 {
   connected_uis = pmap_new(uint64_t)();
+  // Add handler for "attach_ui"
+  String method = cstr_as_string("ui_attach");
+  MsgpackRpcRequestHandler handler = {.fn = remote_ui_attach, .defer = false};
+  msgpack_rpc_add_method_handler(method, handler);
+  method = cstr_as_string("ui_detach");
+  handler.fn = remote_ui_detach;
+  msgpack_rpc_add_method_handler(method, handler);
+  method = cstr_as_string("ui_try_resize");
+  handler.fn = remote_ui_try_resize;
+  msgpack_rpc_add_method_handler(method, handler);
 }
 
-Object remote_ui_attach(uint64_t channel_id, uint64_t request_id, Array args,
-                        Error *error)
+void remote_ui_disconnect(uint64_t channel_id)
+{
+  UI *ui = pmap_get(uint64_t)(connected_uis, channel_id);
+  if (!ui) {
+    return;
+  }
+  UIData *data = ui->data;
+  // destroy pending screen updates
+  api_free_array(data->buffer);
+  pmap_del(uint64_t)(connected_uis, channel_id);
+  free(ui->data);
+  ui_detach(ui);
+  free(ui);
+}
+
+static Object remote_ui_attach(uint64_t channel_id, uint64_t request_id,
+                               Array args, Error *error)
 {
   if (pmap_has(uint64_t)(connected_uis, channel_id)) {
     api_set_error(error, Exception, _("UI already attached for channel"));
     return NIL;
   }
 
-  if (args.size != 2 || args.items[0].type != kObjectTypeInteger
+  if (args.size != 3 || args.items[0].type != kObjectTypeInteger
       || args.items[1].type != kObjectTypeInteger
+      || args.items[2].type != kObjectTypeBoolean
       || args.items[0].data.integer <= 0 || args.items[1].data.integer <= 0) {
     api_set_error(error, Validation,
                   _("Arguments must be a pair of positive integers "
@@ -50,6 +76,7 @@ Object remote_ui_attach(uint64_t channel_id, uint64_t request_id, Array args,
   UI *ui = xcalloc(1, sizeof(UI));
   ui->width = (int)args.items[0].data.integer;
   ui->height = (int)args.items[1].data.integer;
+  ui->rgb = args.items[2].data.boolean;
   ui->data = data;
   ui->resize = remote_ui_resize;
   ui->clear = remote_ui_clear;
@@ -67,16 +94,16 @@ Object remote_ui_attach(uint64_t channel_id, uint64_t request_id, Array args,
   ui->put = remote_ui_put;
   ui->bell = remote_ui_bell;
   ui->visual_bell = remote_ui_visual_bell;
+  ui->update_fg = remote_ui_update_fg;
+  ui->update_bg = remote_ui_update_bg;
   ui->flush = remote_ui_flush;
-  ui->suspend = remote_ui_suspend;
   pmap_put(uint64_t)(connected_uis, channel_id, ui);
   ui_attach(ui);
-
   return NIL;
 }
 
-Object remote_ui_detach(uint64_t channel_id, uint64_t request_id, Array args,
-                        Error *error)
+static Object remote_ui_detach(uint64_t channel_id, uint64_t request_id,
+                               Array args, Error *error)
 {
   if (!pmap_has(uint64_t)(connected_uis, channel_id)) {
     api_set_error(error, Exception, _("UI is not attached for channel"));
@@ -86,21 +113,30 @@ Object remote_ui_detach(uint64_t channel_id, uint64_t request_id, Array args,
   return NIL;
 }
 
-void remote_ui_disconnect(uint64_t channel_id)
+static Object remote_ui_try_resize(uint64_t channel_id, uint64_t request_id,
+                                   Array args, Error *error)
 {
-  UI *ui = pmap_get(uint64_t)(connected_uis, channel_id);
-  if (!ui) {
-    return;
+  if (!pmap_has(uint64_t)(connected_uis, channel_id)) {
+    api_set_error(error, Exception, _("UI is not attached for channel"));
   }
-  UIData *data = ui->data;
-  // destroy pending screen updates
-  api_free_array(data->buffer);
-  pmap_del(uint64_t)(connected_uis, channel_id);
-  free(ui->data);
-  ui_detach(ui);
-  free(ui);
+
+  if (args.size != 2 || args.items[0].type != kObjectTypeInteger
+      || args.items[1].type != kObjectTypeInteger
+      || args.items[0].data.integer <= 0 || args.items[1].data.integer <= 0) {
+    api_set_error(error, Validation,
+                  _("Arguments must be a pair of positive integers "
+                    "representing the remote screen width/height"));
+    return NIL;
+  }
+
+  UI *ui = pmap_get(uint64_t)(connected_uis, channel_id);
+  ui->width = (int)args.items[0].data.integer;
+  ui->height = (int)args.items[1].data.integer;
+  ui_refresh();
+  return NIL;
 }
 
+
 static void push_call(UI *ui, char *name, Array args)
 {
   Array call = ARRAY_DICT_INIT;
@@ -214,10 +250,6 @@ static void remote_ui_highlight_set(UI *ui, HlAttrs attrs)
     PUT(hl, "bold", BOOLEAN_OBJ(true));
   }
 
-  if (attrs.standout) {
-    PUT(hl, "standout", BOOLEAN_OBJ(true));
-  }
-
   if (attrs.underline) {
     PUT(hl, "underline", BOOLEAN_OBJ(true));
   }
@@ -266,15 +298,23 @@ static void remote_ui_visual_bell(UI *ui)
   push_call(ui, "visual_bell", args);
 }
 
-static void remote_ui_flush(UI *ui)
+static void remote_ui_update_fg(UI *ui, int fg)
 {
-  UIData *data = ui->data;
-  channel_send_event(data->channel_id, "redraw", data->buffer);
-  data->buffer = (Array)ARRAY_DICT_INIT;
+  Array args = ARRAY_DICT_INIT;
+  ADD(args, INTEGER_OBJ(fg));
+  push_call(ui, "update_fg", args);
 }
 
-static void remote_ui_suspend(UI *ui)
+static void remote_ui_update_bg(UI *ui, int bg)
+{
+  Array args = ARRAY_DICT_INIT;
+  ADD(args, INTEGER_OBJ(bg));
+  push_call(ui, "update_bg", args);
+}
+
+static void remote_ui_flush(UI *ui)
 {
   UIData *data = ui->data;
-  remote_ui_disconnect(data->channel_id);
+  channel_send_event(data->channel_id, "redraw", data->buffer);
+  data->buffer = (Array)ARRAY_DICT_INIT;
 }
diff --git a/src/nvim/os/input.c b/src/nvim/os/input.c
index c0d588f4ef..130e239a34 100644
--- a/src/nvim/os/input.c
+++ b/src/nvim/os/input.c
@@ -187,14 +187,20 @@ size_t input_enqueue(String keys)
     unsigned int new_size = trans_special((uint8_t **)&ptr, buf, false);
 
     if (!new_size) {
+      if (*ptr == '<') {
+        // Invalid key sequence, skip until the next '>' or until *end
+        do {
+          ptr++;
+        } while (ptr < end && *ptr != '>');
+        ptr++;
+        continue;
+      }
       // copy the character unmodified
       *buf = (uint8_t)*ptr++;
       new_size = 1;
     }
 
     new_size = handle_mouse_event(&ptr, buf, new_size);
-    // TODO(tarruda): Don't produce past unclosed '<' characters, except if
-    // there's a lot of characters after the '<'
     rbuffer_write(input_buffer, (char *)buf, new_size);
   }
 
diff --git a/src/nvim/os/shell.c b/src/nvim/os/shell.c
index d0f8442768..d481d6af56 100644
--- a/src/nvim/os/shell.c
+++ b/src/nvim/os/shell.c
@@ -24,7 +24,6 @@
 #include "nvim/option_defs.h"
 #include "nvim/charset.h"
 #include "nvim/strings.h"
-#include "nvim/ui.h"
 
 #define DYNAMIC_BUFFER_INIT {NULL, 0, 0}
 
@@ -414,6 +413,7 @@ static size_t write_output(char *output, size_t remaining, bool to_buffer,
 
   char *start = output;
   size_t off = 0;
+  int lastrow = (int)Rows - 1;
   while (off < remaining) {
     if (output[off] == NL) {
       // Insert the line
@@ -421,10 +421,8 @@ static size_t write_output(char *output, size_t remaining, bool to_buffer,
       if (to_buffer) {
         ml_append(curwin->w_cursor.lnum++, (char_u *)output, 0, false);
       } else {
-        // pending data from the output buffer has been flushed to the screen,
-        // safe to call ui_write directly
-        ui_write((char_u *)output, (int)off);
-        ui_write((char_u *)"\r\n", 2);
+        screen_del_lines(0, 0, 1, (int)Rows, true, NULL);
+        screen_puts_len((char_u *)output, (int)off, lastrow, 0, 0);
       }
       size_t skip = off + 1;
       output += skip;
@@ -448,8 +446,8 @@ static size_t write_output(char *output, size_t remaining, bool to_buffer,
         // remember that the NL was missing
         curbuf->b_no_eol_lnum = curwin->w_cursor.lnum;
       } else {
-        ui_write((char_u *)output, (int)remaining);
-        ui_write((char_u *)"\r\n", 2);
+        screen_del_lines(0, 0, 1, (int)Rows, true, NULL);
+        screen_puts_len((char_u *)output, (int)remaining, lastrow, 0, 0);
       }
       output += remaining;
     } else if (to_buffer) {
diff --git a/src/nvim/screen.c b/src/nvim/screen.c
index 855c09619e..b593d5a687 100644
--- a/src/nvim/screen.c
+++ b/src/nvim/screen.c
@@ -4548,7 +4548,7 @@ static void screen_line(int row, int coloff, int endcol, int clear_width, int rl
       int c;
 
       c = fillchar_vsep(&hl);
-      if (ScreenLines[off_to] != c
+      if (ScreenLines[off_to] != ((schar_T)c)
           || (enc_utf8 && (int)ScreenLinesUC[off_to]
               != (c >= 0x80 ? c : 0))
           || ScreenAttrs[off_to] != hl) {
@@ -6150,8 +6150,7 @@ void screen_fill(int start_row, int end_row, int start_col, int end_col, int c1,
     return;
 
   /* it's a "normal" terminal when not in a GUI or cterm */
-  norm_term = (
-    t_colors <= 1);
+  norm_term = (!abstract_ui && t_colors <= 1);
   for (row = start_row; row < end_row; ++row) {
     if (has_mbyte
         ) {
@@ -6675,7 +6674,7 @@ static void linecopy(int to, int from, win_T *wp)
  */
 int can_clear(char_u *p)
 {
-  return *p != NUL && (t_colors <= 1
+  return *p != NUL && ((!abstract_ui && t_colors <= 1)
                        || cterm_normal_bg_color == 0 || *T_UT != NUL);
 }
 
@@ -7702,8 +7701,7 @@ static void draw_tabline(void)
   int attr_fill = hl_attr(HLF_TPF);
   char_u      *p;
   int room;
-  int use_sep_chars = (t_colors < 8
-                       );
+  int use_sep_chars = !abstract_ui && t_colors < 8;
 
   redraw_tabline = FALSE;
 
@@ -8188,6 +8186,9 @@ void screen_resize(int width, int height, int mustset)
   check_shellsize();
 
   if (abstract_ui) {
+    // Clear the output buffer to ensure UIs don't receive redraw command meant
+    // for invalid screen sizes.
+    out_buf_clear();
     ui_resize(width, height);
   } else {
     mch_set_shellsize();
diff --git a/src/nvim/syntax.c b/src/nvim/syntax.c
index 4e2be0cd44..80dc99d6e7 100644
--- a/src/nvim/syntax.c
+++ b/src/nvim/syntax.c
@@ -45,6 +45,7 @@
 #include "nvim/strings.h"
 #include "nvim/syntax_defs.h"
 #include "nvim/term.h"
+#include "nvim/ui.h"
 #include "nvim/os/os.h"
 #include "nvim/os/time.h"
 
@@ -5983,7 +5984,7 @@ init_highlight (
    * With 8 colors brown is equal to yellow, need to use black for Search fg
    * to avoid Statement highlighted text disappears.
    * Clear the attributes, needed when changing the t_Co value. */
-  if (t_colors > 8)
+  if (abstract_ui || t_colors > 8)
     do_highlight(
         (char_u *)(*p_bg == 'l'
                    ? "Visual cterm=NONE ctermbg=LightGrey"
@@ -6036,6 +6037,7 @@ int load_colors(char_u *name)
   apply_autocmds(EVENT_COLORSCHEME, name, curbuf->b_fname, FALSE, curbuf);
 
   recursive = FALSE;
+  ui_refresh();
 
   return retval;
 }
@@ -6431,7 +6433,9 @@ do_highlight (
             /* Use the _16 table to check if its a valid color name. */
             color = color_numbers_16[i];
             if (color >= 0) {
-              if (t_colors == 8) {
+              if (abstract_ui) {
+                color = color_numbers_256[i];
+              } else if (t_colors == 8) {
                 /* t_Co is 8: use the 8 colors table */
 #if defined(__QNXNTO__)
                 color = color_numbers_8_qansi[i];
@@ -6448,8 +6452,7 @@ do_highlight (
                     HL_TABLE()[idx].sg_cterm &= ~HL_BOLD;
                 }
                 color &= 7;             /* truncate to 8 colors */
-              } else if (t_colors == 16 || t_colors == 88
-                         || t_colors == 256) {
+              } else if (t_colors == 16 || t_colors == 88 || t_colors == 256) {
                 /*
                  * Guess: if the termcap entry ends in 'm', it is
                  * probably an xterm-like terminal.  Use the changed
@@ -6496,7 +6499,7 @@ do_highlight (
                 if (color >= 0) {
                   if (termcap_active)
                     term_bg_color(color);
-                  if (t_colors < 16)
+                  if (!abstract_ui && t_colors < 16)
                     i = (color == 0 || color == 4);
                   else
                     i = (color < 7 || color == 8);
@@ -6642,6 +6645,10 @@ do_highlight (
     if (is_normal_group) {
       HL_TABLE()[idx].sg_term_attr = 0;
       HL_TABLE()[idx].sg_cterm_attr = 0;
+      if (abstract_ui) {
+        // If the normal group has changed, it is simpler to refresh every UI
+        ui_refresh();
+      }
     } else
       set_hl_attr(idx);
     HL_TABLE()[idx].sg_scriptID = current_SID;
@@ -6870,7 +6877,7 @@ int hl_combine_attr(int char_attr, int prim_attr)
   if (char_attr <= HL_ALL && prim_attr <= HL_ALL)
     return char_attr | prim_attr;
 
-  if (t_colors > 1) {
+  if (abstract_ui || t_colors > 1) {
     if (char_attr > HL_ALL)
       char_aep = syn_cterm_attr2entry(char_attr);
     if (char_aep != NULL)
@@ -6934,7 +6941,7 @@ int syn_attr2attr(int attr)
 {
   attrentry_T *aep;
 
-  if (t_colors > 1)
+  if (abstract_ui || t_colors > 1)
     aep = syn_cterm_attr2entry(attr);
   else
     aep = syn_term_attr2entry(attr);
@@ -7204,9 +7211,10 @@ set_hl_attr (
    * For the color term mode: If there are other than "normal"
    * highlighting attributes, need to allocate an attr number.
    */
-  if (sgp->sg_cterm_fg == 0 && sgp->sg_cterm_bg == 0)
+  if (sgp->sg_cterm_fg == 0 && sgp->sg_cterm_bg == 0
+      && sgp->sg_rgb_fg == -1 && sgp->sg_rgb_bg == -1) {
     sgp->sg_cterm_attr = sgp->sg_cterm;
-  else {
+  } else {
     at_en.ae_attr = abstract_ui ? sgp->sg_gui : sgp->sg_cterm;
     at_en.ae_u.cterm.fg_color = sgp->sg_cterm_fg;
     at_en.ae_u.cterm.bg_color = sgp->sg_cterm_bg;
@@ -7361,7 +7369,7 @@ int syn_id2attr(int hl_id)
   hl_id = syn_get_final_id(hl_id);
   sgp = &HL_TABLE()[hl_id - 1];             /* index is ID minus one */
 
-  if (t_colors > 1)
+  if (abstract_ui || t_colors > 1)
     attr = sgp->sg_cterm_attr;
   else
     attr = sgp->sg_term_attr;
diff --git a/src/nvim/term.c b/src/nvim/term.c
index b7c30300b0..1169435a4f 100644
--- a/src/nvim/term.c
+++ b/src/nvim/term.c
@@ -170,6 +170,7 @@ static struct builtin_term builtin_termcaps[] =
   {(int)KS_DL,   "\033|d"},
   {(int)KS_CDL,  "\033|%p1%dD"},
   {(int)KS_CS,   "\033|%p1%d;%p2%dR"},
+  {(int)KS_CSV,  "\033|%p1%d;%p2%dV"},
   {(int)KS_CL,   "\033|C"},
   // attributes switched on with 'h', off with * 'H'
   {(int)KS_ME,   "\033|31H"},  // HL_ALL
@@ -1817,17 +1818,20 @@ void term_write(char_u *s, size_t len)
 static char_u out_buf[OUT_SIZE + 1];
 static int out_pos = 0;                 /* number of chars in out_buf */
 
+// Clear the output buffer
+void out_buf_clear(void)
+{
+  out_pos = 0;
+}
+
 /*
  * out_flush(): flush the output buffer
  */
 void out_flush(void)
 {
-  if (out_pos != 0) {
-    /* set out_pos to 0 before ui_write, to avoid recursiveness */
-    int len = out_pos;
-    out_pos = 0;
-    ui_write(out_buf, len);
-  }
+  int len = out_pos;
+  out_pos = 0;
+  ui_write(out_buf, len);
 }
 
 /*
diff --git a/src/nvim/ui.c b/src/nvim/ui.c
index 25d6a81960..71960e8a63 100644
--- a/src/nvim/ui.c
+++ b/src/nvim/ui.c
@@ -60,11 +60,8 @@ static struct {
   int top, bot, left, right;
 } sr;
 static int current_highlight_mask = 0;
-static HlAttrs current_attrs = {
-  false, false, false, false, false, false, -1, -1
-};
 static bool cursor_enabled = true;
-static int height = INT_MAX, width = INT_MAX;
+static int height, width;
 
 // This set of macros allow us to use UI_CALL to invoke any function on
 // registered UI instances. The functions can have 0-5 arguments(configurable
@@ -98,6 +95,10 @@ void ui_write(uint8_t *s, int len)
     return;
   }
 
+  if (!len) {
+    return;
+  }
+
   char_u  *tofree = NULL;
 
   if (output_conv.vc_type != CONV_NONE) {
@@ -120,9 +121,7 @@ void ui_write(uint8_t *s, int len)
  */
 void ui_suspend(void)
 {
-  if (abstract_ui) {
-    UI_CALL(suspend);
-  } else {
+  if (!abstract_ui) {
     mch_suspend();
   }
 }
@@ -165,8 +164,31 @@ void ui_cursor_shape(void)
   }
 }
 
-void ui_resize(int width, int height)
+void ui_refresh(void)
+{
+  if (!ui_count) {
+    return;
+  }
+
+  int width = INT_MAX, height = INT_MAX;
+
+  for (size_t i = 0; i < ui_count; i++) {
+    UI *ui = uis[i];
+    width = ui->width < width ? ui->width : width;
+    height = ui->height < height ? ui->height : height;
+  }
+
+  screen_resize(width, height, true);
+}
+
+void ui_resize(int new_width, int new_height)
 {
+  width = new_width;
+  height = new_height;
+
+  UI_CALL(update_fg, (ui->rgb ? normal_fg : cterm_normal_fg_color - 1));
+  UI_CALL(update_bg, (ui->rgb ? normal_bg : cterm_normal_bg_color - 1));
+
   sr.top = 0;
   sr.bot = height - 1;
   sr.left = 0;
@@ -240,7 +262,7 @@ void ui_attach(UI *ui)
   }
 
   uis[ui_count++] = ui;
-  resized(ui);
+  ui_refresh();
 }
 
 void ui_detach(UI *ui)
@@ -267,17 +289,8 @@ void ui_detach(UI *ui)
 
   ui_count--;
 
-  if (ui->width == width || ui->height == height) {
-    // It is possible that the UI being detached had the smallest screen,
-    // so check for the new minimum dimensions
-    width = height = INT_MAX;
-    for (size_t i = 0; i < ui_count; i++) {
-      check_dimensions(uis[i]);
-    }
-  }
-
   if (ui_count) {
-    screen_resize(width, height, true);
+    ui_refresh();
   }
 }
 
@@ -295,8 +308,7 @@ static void highlight_start(int mask)
     return;
   }
 
-  set_highlight_args(current_highlight_mask, &current_attrs);
-  UI_CALL(highlight_set, current_attrs);
+  set_highlight_args(current_highlight_mask);
 }
 
 static void highlight_stop(int mask)
@@ -309,12 +321,12 @@ static void highlight_stop(int mask)
     current_highlight_mask &= ~mask;
   }
 
-  set_highlight_args(current_highlight_mask, &current_attrs);
-  UI_CALL(highlight_set, current_attrs);
+  set_highlight_args(current_highlight_mask);
 }
 
-static void set_highlight_args(int mask, HlAttrs *attrs)
+static void set_highlight_args(int mask)
 {
+  HlAttrs rgb_attrs = { false, false, false, false, false, -1, -1 };
   attrentry_T *aep = NULL;
 
   if (mask > HL_ALL) {
@@ -322,18 +334,40 @@ static void set_highlight_args(int mask, HlAttrs *attrs)
     mask = aep ? aep->ae_attr : 0;
   }
 
-  attrs->bold = mask & HL_BOLD;
-  attrs->standout = mask & HL_STANDOUT;
-  attrs->underline = mask & HL_UNDERLINE;
-  attrs->undercurl = mask & HL_UNDERCURL;
-  attrs->italic = mask & HL_ITALIC;
-  attrs->reverse = mask & HL_INVERSE;
-  attrs->foreground = aep && aep->fg_color >= 0 ? aep->fg_color : normal_fg;
-  attrs->background = aep && aep->bg_color >= 0 ? aep->bg_color : normal_bg;
+  rgb_attrs.bold = mask & HL_BOLD;
+  rgb_attrs.underline = mask & HL_UNDERLINE;
+  rgb_attrs.undercurl = mask & HL_UNDERCURL;
+  rgb_attrs.italic = mask & HL_ITALIC;
+  rgb_attrs.reverse = mask & (HL_INVERSE | HL_STANDOUT);
+  HlAttrs cterm_attrs = rgb_attrs;
+
+  if (aep) {
+    if (aep->fg_color != normal_fg) {
+      rgb_attrs.foreground = aep->fg_color;
+    }
+
+    if (aep->bg_color != normal_bg) {
+      rgb_attrs.background = aep->bg_color;
+    }
+
+    if (cterm_normal_fg_color != aep->ae_u.cterm.fg_color) {
+      cterm_attrs.foreground = aep->ae_u.cterm.fg_color - 1;
+    }
+
+    if (cterm_normal_bg_color != aep->ae_u.cterm.bg_color) {
+      cterm_attrs.background = aep->ae_u.cterm.bg_color - 1;
+    }
+  }
+
+  UI_CALL(highlight_set, (ui->rgb ? rgb_attrs : cterm_attrs));
 }
 
 static void parse_abstract_ui_codes(uint8_t *ptr, int len)
 {
+  if (!ui_count) {
+    return;
+  }
+
   int arg1 = 0, arg2 = 0;
   uint8_t *end = ptr + len, *p, c;
   bool update_cursor = false;
@@ -444,6 +478,9 @@ static void parse_abstract_ui_codes(uint8_t *ptr, int len)
           UI_CALL(put, NULL, 0);
           col++;
         }
+        if (col >= width) {
+          ui_linefeed();
+        }
         p += clen;
       }
       ptr = p;
@@ -457,25 +494,6 @@ static void parse_abstract_ui_codes(uint8_t *ptr, int len)
   UI_CALL(flush);
 }
 
-static void resized(UI *ui)
-{
-  check_dimensions(ui);
-  screen_resize(width, height, true);
-}
-
-static void check_dimensions(UI *ui)
-{
-  // The internal screen dimensions are always the minimum required to fit on
-  // all connected screens
-  if (ui->width < width) {
-    width = ui->width;
-  }
-
-  if (ui->height < height) {
-    height = ui->height;
-  }
-}
-
 static void ui_linefeed(void)
 {
   int new_col = 0;
diff --git a/src/nvim/ui.h b/src/nvim/ui.h
index d0933055cc..3d3e2f4ffc 100644
--- a/src/nvim/ui.h
+++ b/src/nvim/ui.h
@@ -6,13 +6,14 @@
 #include <stdint.h>
 
 typedef struct {
-  bool bold, standout, underline, undercurl, italic, reverse;
+  bool bold, underline, undercurl, italic, reverse;
   int foreground, background;
 } HlAttrs;
 
 typedef struct ui_t UI;
 
 struct ui_t {
+  bool rgb;
   int width, height;
   void *data;
   void (*resize)(UI *ui, int rows, int columns);
@@ -32,7 +33,8 @@ struct ui_t {
   void (*bell)(UI *ui);
   void (*visual_bell)(UI *ui);
   void (*flush)(UI *ui);
-  void (*suspend)(UI *ui);
+  void (*update_fg)(UI *ui, int fg);
+  void (*update_bg)(UI *ui, int bg);
 };
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS