display modal form in the bootstrap4 theme

flask_admin/static/admin/js/bs4_modal.js

+// fixes "content does not load remote modal on clicked modal button"
+$('body').on('click.modal.data-api', '[data-toggle="modal"]', function () {
+    $($(this).data("target") + ' .modal-content').load($(this).attr('href'));
+});
\ No newline at end of file

flask_admin/templates/bootstrap4/admin/base.html

@@ -67,7 +67,7 @@
   {% endblock %}
 
     {% block tail_js %}
-    <script src="{{ admin_static.url(filename='vendor/jquery-3.3.1.slim.min.js', v='2.1.4') }}" type="text/javascript"></script>
+    <script src="{{ admin_static.url(filename='vendor/jquery.min.js', v='2.1.4') }}" type="text/javascript"></script>
     <script src="{{ admin_static.url(filename='bootstrap/bootstrap4/popper.min.js') }}" type="text/javascript"></script>
     <script src="{{ admin_static.url(filename='bootstrap/bootstrap4/bootstrap.min.js', v='4.1.2') }}" type="text/javascript"></script>
     <script src="{{ admin_static.url(filename='vendor/moment.min.js', v='2.9.0') }}" type="text/javascript"></script>

flask_admin/templates/bootstrap4/admin/model/list.html

@@ -180,6 +180,7 @@
 
 {% block tail %}
     {{ super() }}
+    <script src="{{ admin_static.url(filename='admin/js/bs4_modal.js', v='1.0.0') }}"></script>
     <script src="{{ admin_static.url(filename='admin/js/filters.js', v='1.0.0') }}"></script>
     {{ lib.form_js() }}