Add Multi Class to inline add button

_config/gridfieldextensions.yml

@@ -2,4 +2,8 @@
 name: gridfieldextensions
 ---
 GridFieldAddNewMultiClass:
-  showEmptyString: true
+  showEmptyString: true
+
+SilverStripe\Forms\GridField\GridFieldDetailForm_ItemRequest:
+  extensions:
+    - Symbiote\GridFieldExtensions\Extensions\GridFieldDetailFormItemRequestExtension

css/GridFieldExtensions.css

@@ -201,3 +201,25 @@
 .ss-gridfield-configurable-paginator .pagination-page-number input {
   text-align: center;
 }
+
+.grid-field-inline-new--multi-class-list {
+  display: none;
+  background-color: #008a00;
+  border-radius: 5px;
+  bottom: 3em;
+  list-style: none;
+  margin: 0;
+  right: 3em;
+  padding: 10px;
+  position: fixed;
+
+}
+.grid-field-inline-new--multi-class-list a {
+  color: #FFF;
+  display: block;
+  margin: 5px -10px;
+  padding: 0 10px;
+}
+.grid-field-inline-new--multi-class-list__visible {
+  display: block;
+}

javascript/GridFieldExtensions.js

@@ -237,6 +237,24 @@
 			}
 		});
 
+		$(".action--new__multi-class").entwine({
+			onmatch: function () {
+				const hrefTemplate = this.data('hrefTemplate');
+				const classes = this.data('classes');
+				const liHtml = Object.keys(classes).map(className => {
+					const link = hrefTemplate.replace('{class}', className);
+					return `<li><a href="${link}">Add: <i>${classes[className]}</i></a></li>`;
+				});
+
+				const listElement = $(`<ul class="grid-field-inline-new--multi-class-list">${liHtml.join('')}</ul>`);
+				listElement.insertBefore(this);
+
+				this.on('click', function () {
+					listElement.toggleClass('grid-field-inline-new--multi-class-list__visible');
+				});
+			},
+		});
+
 		$(".ss-gridfield-add-new-multi-class select").entwine({
 			onadd: function() {
 				this.update();

src/Extensions/GridFieldDetailFormItemRequestExtension.php

@@ -0,0 +1,83 @@
+<?php
+
+namespace Symbiote\GridFieldExtensions\Extensions;
+
+use SilverStripe\Control\Controller;
+use SilverStripe\Core\Convert;
+use SilverStripe\Core\Extension;
+use SilverStripe\Forms\FieldList;
+use SilverStripe\Forms\GridField\GridFieldDetailForm_ItemRequest as CoreGridFieldDetailForm_ItemRequest;
+use SilverStripe\Forms\LiteralField;
+use SilverStripe\View\ArrayData;
+use SilverStripe\View\HTML;
+use Symbiote\GridFieldExtensions\GridFieldAddNewMultiClass;
+use Symbiote\GridFieldExtensions\GridFieldExtensions;
+
+/**
+ * @property CoreGridFieldDetailForm_ItemRequest $owner
+ */
+class GridFieldDetailFormItemRequestExtension extends Extension
+{
+    /**
+     * @param FieldList $actions
+     */
+    public function updateFormActions(FieldList &$actions)
+    {
+        $grid = $this->owner->getGridField();
+        $gridFieldConfig = $grid->getConfig();
+        $addMultiClassComponent = $gridFieldConfig->getComponentByType(GridFieldAddNewMultiClass::class);
+        if ($addMultiClassComponent) {
+            $newRecordField = static::get_new_record_field_from_actions($actions);
+            if ($newRecordField) {
+                $newRecordField->getContainerFieldList()->removeByName('new-record');
+                $newRecordField->getContainerFieldList()->push(
+                    LiteralField::create('new-record', $this->getHTMLFragment($addMultiClassComponent))
+                );
+                GridFieldExtensions::include_requirements();
+            }
+        }
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    private function getHTMLFragment(GridFieldAddNewMultiClass $component)
+    {
+        $grid = $this->owner->getGridField();
+
+        $classes = $component->getClasses($grid);
+
+        if (!count($classes)) {
+            return false;
+        }
+
+        return HTML::createTag('a', [
+            'data-href-template' => Controller::join_links($grid->Link(), 'add-multi-class', '{class}'),
+            'title' => _t(__CLASS__ . '.NEW', 'Add new record'),
+            'aria-label' => _t(__CLASS__ . '.NEW', 'Add new record'),
+            'class' => implode(' ', array(
+                'btn',
+                'btn-primary',
+                'font-icon-plus-thin',
+                'btn--circular',
+                'action--new',
+                'discard-confirmation',
+                'action--new__multi-class',
+            )),
+            'data-classes' => Convert::array2json($classes),
+        ]);
+    }
+
+    /**
+     * @param FieldList $actions
+     * @return LiteralField OR NULL
+     */
+    private static function get_new_record_field_from_actions(FieldList &$actions)
+    {
+        $rightGroup = $actions->fieldByName('RightGroup');
+        if (!$rightGroup) {
+            return null;
+        }
+        return $rightGroup->getChildren()->fieldByName('new-record');
+    }
+}