fix: make dashboard widgets closable (#14)

Every GridStackItem now renders a close button next to its drag grip,
mirroring the grip's hover affordance. Closing detaches the item
server-side; grid-stack.ts already unregisters widgets via its
MutationObserver, so the layout is persisted without an extra protocol.

Closable is on by default and can be turned off per item with
setClosable(false); GridStackItem.CloseEvent lets views react.

The GridStackView "remove last" toolbar button is dropped — per-widget
close replaces it, so the view no longer tracks a widget stack. Its
counter now only grows, keeping a closed widget's id from being handed
to a new widget (which would inherit the saved position).

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ue9ZtWUBQF4SuSHpzZ3zwq

src/main/java/com/example/components/Fa.java

@@ -25,7 +25,8 @@ public enum Fa {
     ADD("fa-solid", "fa-plus"),
     REMOVE("fa-solid", "fa-trash"),
     RESET("fa-solid", "fa-arrow-rotate-left"),
-    DRAG("fa-solid", "fa-grip-vertical");
+    DRAG("fa-solid", "fa-grip-vertical"),
+    CLOSE("fa-solid", "fa-xmark");
 
     private final String[] classes;
 

src/main/java/com/example/components/GridStackItem.java

@@ -1,7 +1,10 @@
 package com.example.components;
 
 import com.vaadin.flow.component.Component;
+import com.vaadin.flow.component.ComponentEvent;
+import com.vaadin.flow.component.ComponentEventListener;
 import com.vaadin.flow.component.html.Div;
+import com.vaadin.flow.shared.Registration;
 
 import java.util.UUID;
 
@@ -12,7 +15,10 @@ import java.util.UUID;
  * <p>
  * Dragging starts from the grip handle only, never from the item body, so the
  * components inside an item stay interactive (see
- * {@link GridStackLayout#setDragHandle(String)}).
+ * {@link GridStackLayout#setDragHandle(String)}). A close button sits next to
+ * the grip (see {@link #setClosable(boolean)}); removing the item server-side
+ * is enough to unregister the widget client-side, since grid-stack.ts observes
+ * its own childList.
  */
 public class GridStackItem extends Div {
 
@@ -20,8 +26,14 @@ public class GridStackItem extends Div {
      *  {@link GridStackLayout}'s {@code handle} option. */
     public static final String DRAG_HANDLE_CLASS = "dialect-drag-handle";
 
+    /** Marker class for the close button; {@code styles.css} keys both its own
+     *  styling and the grip's offset off it. */
+    public static final String CLOSE_BUTTON_CLASS = "dialect-close-button";
+
     private final Div content = new Div();
     private final Div dragHandle = new Div();
+    private final Div closeButton = new Div();
+    private boolean closable = true;
 
     public GridStackItem(Component... content) {
         this(UUID.randomUUID().toString(), 0, 0, 4, 3, content);
@@ -51,6 +63,72 @@ public class GridStackItem extends Div {
         dragHandle.getElement().setAttribute("title", label);
         dragHandle.getElement().setAttribute("aria-label", label);
         getElement().appendChild(dragHandle.getElement());
+
+        // Sibling of the content wrapper for the same reason as the grip, and
+        // outside the drag-handle selector so clicking it never starts a drag.
+        closeButton.addClassName(CLOSE_BUTTON_CLASS);
+        closeButton.add(Fa.CLOSE.create());
+        String closeLabel = getTranslation("gridstack.close");
+        closeButton.getElement().setAttribute("title", closeLabel);
+        closeButton.getElement().setAttribute("aria-label", closeLabel);
+        closeButton.getElement().setAttribute("role", "button");
+        closeButton.getElement().setAttribute("tabindex", "0");
+        closeButton.getElement().addEventListener("click", e -> close(true));
+        closeButton.getElement().addEventListener("keydown", e -> close(true))
+                .setFilter("event.key === 'Enter' || event.key === ' '");
+        getElement().appendChild(closeButton.getElement());
+    }
+
+    /**
+     * Detaches this item from its layout and notifies
+     * {@link #addCloseListener(ComponentEventListener) close listeners}. Called
+     * by the close button, and usable server-side to close an item
+     * programmatically.
+     */
+    public void close() {
+        close(false);
+    }
+
+    private void close(boolean fromClient) {
+        // Detach first so listeners observe the layout they are about to see —
+        // getLayout() on the grid no longer counts this item.
+        getElement().removeFromParent();
+        fireEvent(new CloseEvent(this, fromClient));
+    }
+
+    /** Shows or hides the close button (shown by default). */
+    public GridStackItem setClosable(boolean closable) {
+        if (closable == this.closable) {
+            return this;
+        }
+        this.closable = closable;
+        if (closable) {
+            getElement().appendChild(closeButton.getElement());
+        } else {
+            closeButton.getElement().removeFromParent();
+        }
+        return this;
+    }
+
+    public boolean isClosable() {
+        return closable;
+    }
+
+    /** The close button element. Exposed for restyling, the same way
+     *  {@link #getDragHandle()} is. */
+    public Div getCloseButton() {
+        return closeButton;
+    }
+
+    public Registration addCloseListener(ComponentEventListener<CloseEvent> listener) {
+        return addListener(CloseEvent.class, listener);
+    }
+
+    /** Fired after the item has been removed from its {@link GridStackLayout}. */
+    public static class CloseEvent extends ComponentEvent<GridStackItem> {
+        CloseEvent(GridStackItem source, boolean fromClient) {
+            super(source, fromClient);
+        }
     }
 
     public void add(Component... components) {

src/main/java/com/example/views/GridStackView.java

@@ -18,14 +18,13 @@ import com.vaadin.flow.component.orderedlayout.VerticalLayout;
 import com.vaadin.flow.router.HasDynamicTitle;
 import com.vaadin.flow.router.Route;
 
-import java.util.ArrayDeque;
-import java.util.Deque;
 import java.util.List;
 
 /**
  * Showcase for {@link GridStackLayout}: a dashboard of draggable/resizable
- * cards whose layout is persisted per browser, plus controls to add, remove
- * and reset widgets at runtime.
+ * cards whose layout is persisted per browser, plus controls to add widgets and
+ * reset the layout at runtime. Widgets are removed by their own close button
+ * (see {@link GridStackItem#setClosable(boolean)}), not from the toolbar.
  */
 @Route("gridstack")
 public class GridStackView extends VerticalLayout implements HasDynamicTitle {
@@ -33,7 +32,6 @@ public class GridStackView extends VerticalLayout implements HasDynamicTitle {
     private static final String STORAGE_KEY = "gridstack-demo";
 
     private final GridStackLayout grid = new GridStackLayout();
-    private final Deque<GridStackItem> extraWidgets = new ArrayDeque<>();
     private final Span status = new Span();
     private int extraWidgetCount;
 
@@ -67,13 +65,10 @@ public class GridStackView extends VerticalLayout implements HasDynamicTitle {
                 e -> addWidget());
         add.addThemeVariants(ButtonVariant.LUMO_PRIMARY);
 
-        Button remove = new Button(getTranslation("gridstack.removeWidget"), Fa.REMOVE.create(),
-                e -> removeWidget());
-
         Button reset = new Button(getTranslation("gridstack.reset"), Fa.RESET.create(),
                 e -> grid.resetLayout());
 
-        HorizontalLayout toolbar = new HorizontalLayout(add, remove, reset, status);
+        HorizontalLayout toolbar = new HorizontalLayout(add, reset, status);
         toolbar.setPadding(false);
         toolbar.setWidthFull();
         toolbar.setAlignItems(Alignment.CENTER);
@@ -83,21 +78,13 @@ public class GridStackView extends VerticalLayout implements HasDynamicTitle {
     private void addWidget() {
         // The id must stay stable across reloads for the saved layout to match
         // it again, so it is derived from a counter rather than a random UUID.
+        // The counter only ever grows: closing a widget must not hand its id to
+        // the next one, or the new widget would inherit the closed one's saved
+        // position.
         extraWidgetCount++;
         String title = getTranslation("gridstack.widget", extraWidgetCount);
-        GridStackItem item = new GridStackItem("extra-" + extraWidgetCount, 0, 0, 4, 2,
-                new Card(title, new Paragraph(getTranslation("gridstack.widgetText"))));
-        extraWidgets.push(item);
-        grid.add(item);
-    }
-
-    private void removeWidget() {
-        GridStackItem item = extraWidgets.poll();
-        if (item == null) {
-            return;
-        }
-        grid.remove(item);
-        extraWidgetCount--;
+        grid.add(new GridStackItem("extra-" + extraWidgetCount, 0, 0, 4, 2,
+                new Card(title, new Paragraph(getTranslation("gridstack.widgetText")))));
     }
 
     private Component lineChart() {

src/main/resources/META-INF/resources/styles.css

@@ -176,9 +176,45 @@ vaadin-app-layout::part(content) {
   opacity: 1;
 }
 
-/* Touch devices never hover — keep the grip permanently visible there. */
+/* Close button (GridStackItem#setClosable): same affordance as the grip, in
+   the outermost corner slot. The grip steps aside only when it is there, so a
+   non-closable item keeps its grip flush with the corner. */
+.dialect-close-button {
+  position: absolute;
+  top: 14px;
+  right: 16px;
+  z-index: 1;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 28px;
+  height: 28px;
+  border-radius: 6px;
+  color: var(--dialect-ink);
+  opacity: 0;
+  cursor: pointer;
+  transition: opacity 120ms ease;
+}
+
+.grid-stack-item:has(> .dialect-close-button) > .dialect-drag-handle {
+  right: 48px;
+}
+
+.grid-stack-item:hover > .dialect-close-button,
+.dialect-close-button:focus-visible {
+  opacity: 0.65;
+}
+
+.dialect-close-button:hover,
+.dialect-close-button:active {
+  opacity: 1;
+  color: var(--dialect-primary);
+}
+
+/* Touch devices never hover — keep the corner controls permanently visible. */
 @media (pointer: coarse) {
-  .dialect-drag-handle {
+  .dialect-drag-handle,
+  .dialect-close-button {
     opacity: 0.65;
   }
 }

src/main/resources/vaadin-i18n/translations.properties

@@ -24,15 +24,15 @@ card.registration=Registrierung
 card.employees=Mitarbeiter
 card.gridstackHint=Bedienung
 
-gridstack.hint=Karten am Griff oben rechts verschieben, an der unteren rechten Ecke die Größe ändern. Das Layout wird im Browser gespeichert und beim nächsten Besuch wiederhergestellt.
+gridstack.hint=Karten am Griff oben rechts verschieben, an der unteren rechten Ecke die Größe ändern, mit dem X oben rechts schließen. Das Layout wird im Browser gespeichert und beim nächsten Besuch wiederhergestellt.
 gridstack.addWidget=Widget hinzufügen
-gridstack.removeWidget=Letztes entfernen
 gridstack.reset=Layout zurücksetzen
 gridstack.status=Layout geändert – {0} Widgets
 gridstack.statusInitial=Layout unverändert
 gridstack.widget=Widget {0}
 gridstack.widgetText=Frei platzierbare Karte.
 gridstack.dragHandle=Verschieben
+gridstack.close=Schließen
 
 chart.revenueSeries=Umsatz 2026
 chart.pointClick=Serie {0}, Punkt {1}

src/main/resources/vaadin-i18n/translations_en.properties

@@ -24,15 +24,15 @@ card.registration=Registration
 card.employees=Employees
 card.gridstackHint=How it works
 
-gridstack.hint=Move cards with the grip in their top right corner, resize them from the bottom right corner. The layout is stored in your browser and restored on your next visit.
+gridstack.hint=Move cards with the grip in their top right corner, resize them from the bottom right corner, close them with the X in the top right corner. The layout is stored in your browser and restored on your next visit.
 gridstack.addWidget=Add widget
-gridstack.removeWidget=Remove last
 gridstack.reset=Reset layout
 gridstack.status=Layout changed – {0} widgets
 gridstack.statusInitial=Layout unchanged
 gridstack.widget=Widget {0}
 gridstack.widgetText=Freely placeable card.
 gridstack.dragHandle=Move
+gridstack.close=Close
 
 chart.revenueSeries=Revenue 2026
 chart.pointClick=Series {0}, point {1}

src/main/resources/vaadin-i18n/translations_es.properties

@@ -24,15 +24,15 @@ card.registration=Registro
 card.employees=Empleados
 card.gridstackHint=Cómo funciona
 
-gridstack.hint=Mueve las tarjetas con el asa de la esquina superior derecha y cambia su tamaño desde la esquina inferior derecha. El diseño se guarda en el navegador y se restaura en la próxima visita.
+gridstack.hint=Mueve las tarjetas con el asa de la esquina superior derecha, cambia su tamaño desde la esquina inferior derecha y ciérralas con la X de la esquina superior derecha. El diseño se guarda en el navegador y se restaura en la próxima visita.
 gridstack.addWidget=Añadir widget
-gridstack.removeWidget=Quitar el último
 gridstack.reset=Restablecer diseño
 gridstack.status=Diseño modificado – {0} widgets
 gridstack.statusInitial=Diseño sin cambios
 gridstack.widget=Widget {0}
 gridstack.widgetText=Tarjeta de colocación libre.
 gridstack.dragHandle=Mover
+gridstack.close=Cerrar
 
 chart.revenueSeries=Ingresos 2026
 chart.pointClick=Serie {0}, punto {1}