fix(dashboard): Document expected icon behaviour

Signed-off-by: Joas Schilling <coding@schilljs.com>

lib/private/Dashboard/Manager.php

@@ -25,18 +25,23 @@ class Manager implements IManager {
 	/** @var array<string, IWidget> */
 	private array $widgets = [];
 
-	private ContainerInterface $serverContainer;
 	private ?IAppManager $appManager = null;
 
-	public function __construct(ContainerInterface $serverContainer) {
-		$this->serverContainer = $serverContainer;
+	public function __construct(
+		private ContainerInterface $serverContainer,
+		private LoggerInterface $logger,
+	) {
 	}
 
 	private function registerWidget(IWidget $widget): void {
 		if (array_key_exists($widget->getId(), $this->widgets)) {
 			throw new InvalidArgumentException('Dashboard widget with this id has already been registered');
 		}
 
+		if (!preg_match('/^[a-z][a-z0-9\-_]*$/', $widget->getId())) {
+			$this->logger->debug('Deprecated dashboard widget ID provided: "' . $widget->getId() . '" [ ' . get_class($widget) . ' ]. Please use a-z, 0-9, - and _ only, starting with a-z');
+		}
+
 		$this->widgets[$widget->getId()] = $widget;
 	}
 

lib/public/Dashboard/IIconWidget.php

@@ -14,7 +14,9 @@
  */
 interface IIconWidget extends IWidget {
 	/**
-	 * Get the absolute url for the widget icon
+	 * Get the absolute url for the widget icon (should be colored black or not have a color)
+	 *
+	 * The icon will be inverted automatically in mobile clients and when using dark mode
 	 *
 	 * @return string
 	 * @since 25.0.0

lib/public/Dashboard/IWidget.php

@@ -15,7 +15,12 @@
  */
 interface IWidget {
 	/**
-	 * @return string Unique id that identifies the widget, e.g. the app id
+	 * Get a unique identifier for the widget
+	 *
+	 * To ensure uniqueness, it is recommended to user the app id or start with the
+	 * app id followed by a dash.
+	 *
+	 * @return string Unique id that identifies the widget, e.g. the app id. Only use alphanumeric characters, dash and underscore
 	 * @since 20.0.0
 	 */
 	public function getId(): string;
@@ -33,6 +38,13 @@ public function getTitle(): string;
 	public function getOrder(): int;
 
 	/**
+	 * CSS class that shows the widget icon (should be colored black or not have a color)
+	 *
+	 * The icon will be inverted automatically in mobile clients and when using dark mode.
+	 * Therefore, it is NOT recommended to use a css class that sets the background with:
+	 * `var(--icon-…)` as those will adapt to dark/bright mode in the web and still be inverted
+	 * resulting in a dark icon on dark background.
+	 *
 	 * @return string css class that displays an icon next to the widget title
 	 * @since 20.0.0
 	 */