fix(ui-ext): send title to newly-attached UI

src/nvim/buffer.c

@@ -3444,7 +3444,6 @@ void resettitle(void)
 {
   ui_call_set_icon(cstr_as_string(lasticon));
   ui_call_set_title(cstr_as_string(lasttitle));
-  ui_flush();
 }
 
 #if defined(EXITFREE)

src/nvim/ex_docmd.c

@@ -4875,9 +4875,6 @@ static void ex_stop(exarg_T *eap)
   ui_call_suspend();
   ui_flush();
 
-  maketitle();
-  resettitle();  // force updating the title
-  ui_refresh();  // may have resized window
   apply_autocmds(EVENT_VIMRESUME, NULL, NULL, false, NULL);
 }
 

src/nvim/ui.c

@@ -15,7 +15,7 @@
 #include "nvim/api/ui.h"
 #include "nvim/ascii.h"
 #include "nvim/autocmd.h"
-#include "nvim/buffer_defs.h"
+#include "nvim/buffer.h"
 #include "nvim/cursor_shape.h"
 #include "nvim/drawscreen.h"
 #include "nvim/ex_getln.h"
@@ -348,6 +348,7 @@ void ui_attach_impl(UI *ui, uint64_t chanid)
 
   uis[ui_count++] = ui;
   ui_refresh_options();
+  resettitle();
 
   for (UIExtension i = kUIGlobalCount; (int)i < kUIExtCount; i++) {
     ui_set_ext_option(ui, i, ui->ui_ext[i]);

test/functional/ui/screen_basic_spec.lua

@@ -117,6 +117,12 @@ local function screen_tests(linegrid)
       screen:expect(function()
         eq(expected, screen.title)
       end)
+      screen:detach()
+      screen.title = nil
+      screen:attach()
+      screen:expect(function()
+        eq(expected, screen.title)
+      end)
     end)
   end)
 
@@ -128,6 +134,12 @@ local function screen_tests(linegrid)
       screen:expect(function()
         eq(expected, screen.icon)
       end)
+      screen:detach()
+      screen.icon = nil
+      screen:attach()
+      screen:expect(function()
+        eq(expected, screen.icon)
+      end)
     end)
   end)