Update widget on click dropdown item when creating epic from epic

app/assets/javascripts/vue_shared/components/split_button.vue

@@ -67,7 +67,10 @@ export default {
         :key="item.eventName"
         :active="selectedItem === item"
         active-class="is-active"
-        @click="selectedItem = item"
+        @click="
+          selectedItem = item;
+          triggerEvent();
+        "
       >
         <strong>{{ item.title }}</strong>
         <div>{{ item.description }}</div>

changelogs/unreleased/119341-automatically-update-widget-when-creating-a-new-epic-or-issue-from.yml

+---
+title: Update widget on click dropdown item when creating epic from epic
+merge_request: 22511
+author:
+type: fixed

ee/spec/features/epics/epic_issues_spec.rb

@@ -98,6 +98,15 @@ describe 'Epic Issues', :js do
       visit_epic
     end
 
+    it 'user can display create new epic form by clicking the dropdown item' do
+      expect(page).not_to have_selector('input[placeholder="New epic title"]')
+
+      find('.related-items-tree-container .js-add-epics-button .dropdown-toggle').click
+      find('.related-items-tree-container .js-add-epics-button .dropdown-item', text: 'Create new epic').click
+
+      expect(page).to have_selector('input[placeholder="New epic title"]')
+    end
+
     it 'user can see all issues of the group and delete the associations' do
       within('.related-items-tree-container ul.related-items-list') do
         expect(page).to have_selector('li.js-item-type-issue', count: 2)