fix(job-control): make jobwait() flush UI after hiding cursor (#25927)

src/nvim/eval/funcs.c

@@ -4187,6 +4187,7 @@ static void f_jobwait(typval_T *argvars, typval_T *rettv, EvalFuncData fptr)
   }
 
   ui_busy_start();
+  ui_flush();
   list_T *args = argvars[0].vval.v_list;
   Channel **jobs = xcalloc((size_t)tv_list_len(args), sizeof(*jobs));
   MultiQueue *waiting_jobs = multiqueue_new_parent(loop_on_put, &main_loop);

test/functional/core/job_spec.lua

@@ -700,7 +700,7 @@ describe('jobs', function()
     os.remove('Xtest_jobstart_env')
   end)
 
-  describe('jobwait', function()
+  describe('jobwait()', function()
     before_each(function()
       if is_os('win') then
         helpers.set_shell_powershell()
@@ -874,6 +874,27 @@ describe('jobs', function()
         eq({'notification', 'wait', {{-1, -1}}}, next_msg())
       end)
     end)
+
+    it('hides cursor when waiting', function()
+      local screen = Screen.new(30, 3)
+      screen:set_default_attr_ids({
+        [0] = {foreground = Screen.colors.Blue1, bold = true};
+      })
+      screen:attach()
+      command([[let g:id = jobstart([v:progpath, '--clean', '--headless'])]])
+      feed_command('call jobwait([g:id], 300)')
+      screen:expect{grid=[[
+                                      |
+        {0:~                             }|
+        :call jobwait([g:id], 300)    |
+      ]], timeout=100}
+      funcs.jobstop(meths.get_var('id'))
+      screen:expect{grid=[[
+        ^                              |
+        {0:~                             }|
+        :call jobwait([g:id], 300)    |
+      ]]}
+    end)
   end)
 
   pending('exit event follows stdout, stderr', function()