Issue #3488167 by grimreaper, pdureau: Display prop/slot description in forms

src/Element/ComponentFormBase.php

@@ -42,6 +42,7 @@ abstract class ComponentFormBase extends FormElementBase implements TrustedCallb
       $element[$prop_or_slot_id] = [
         "#type" => "details",
         "#title" => $title,
+        "#description" => $element["#description"] ?? NULL,
         "#open" => FALSE,
       ];
     }

src/Element/ComponentPropsForm.php

@@ -86,6 +86,7 @@ class ComponentPropsForm extends ComponentFormBase {
       $element[$prop_id] = [
         '#type' => 'component_prop_form',
         '#title' => $prop["title"] ?? $prop_type->label(),
+        '#description' => $prop["description"] ?? $prop_type->getPluginDefinition()['description'] ?? NULL,
         '#default_value' => $configuration[$prop_id] ?? [],
         '#source_contexts' => $contexts,
         '#tag_filter' => $element['#tag_filter'],

src/Element/ComponentSlotsForm.php

@@ -80,6 +80,7 @@ class ComponentSlotsForm extends ComponentFormBase {
       $element[$slot_id] = [
         '#title' => $slot['title'] ?? '',
         '#type' => 'component_slot_form',
+        '#description' => $slot["description"] ?? NULL,
         '#default_value' => $configuration[$slot_id] ?? [],
         '#component_id' => $component->getPluginId(),
         '#slot_id' => $slot_id,