Markdown Editor: adds "Default value" support (#18326)

src/Umbraco.Web.UI.Client/src/packages/markdown-editor/property-editors/markdown-editor/manifests.ts

@@ -24,7 +24,7 @@ export const manifests: Array<UmbExtensionManifest> = [
 						alias: 'defaultValue',
 						label: 'Default value',
 						description: 'If value is blank, the editor will show this',
-						propertyEditorUiAlias: 'Umb.PropertyEditorUi.TextArea',
+						propertyEditorUiAlias: 'Umb.PropertyEditorUi.MarkdownEditor',
 					},
 					{
 						alias: 'overlaySize',

src/Umbraco.Web.UI.Client/src/packages/markdown-editor/property-editors/markdown-editor/property-editor-ui-markdown-editor.element.ts

@@ -39,6 +39,12 @@ export class UmbPropertyEditorUIMarkdownEditorElement extends UmbLitElement impl
 
 		this._preview = config.getValueByAlias('preview');
 		this._overlaySize = config.getValueByAlias('overlaySize') ?? 'small';
+
+		// TODO: To be removed once the "Property Value Presets" feature has been implemented.
+		const defaultValue = config.getValueByAlias<string>('defaultValue');
+		if (defaultValue && this.value === undefined) {
+			this.value = defaultValue;
+		}
 	}
 
 	#onChange(event: Event & { target: UmbInputMarkdownElement }) {