Add JFace snippet for a notification popup that follows its shell

Snippet086 keeps a NotificationPopup anchored to the bottom-right corner of a top-level shell by re-positioning it from a ControlListener whenever the shell is moved or resized.

Author: vogella

docs/JFaceSnippets.md

@@ -67,6 +67,10 @@ Demonstrates a `NotificationPopup` with interactive content — a label and a bu
 
 ![Snippet085.png](images/Snippet085NotificationPopupWithUserInteraction.png)
 
+### [Snippet086 - Notification Popup that Follows its Shell](https://github.com/eclipse-platform/eclipse.platform.ui/blob/master/examples/org.eclipse.jface.snippets/Eclipse%20JFace%20Snippets/org/eclipse/jface/snippets/notifications/Snippet086NotificationPopupFollowsShell.java)
+
+Shows how to keep a `NotificationPopup` anchored to the bottom-right corner of a top-level shell by re-positioning it from a `ControlListener` when the shell is moved or resized.
+
 
 Layout
 ------

examples/org.eclipse.jface.snippets/Eclipse JFace Snippets/org/eclipse/jface/snippets/notifications/Snippet086NotificationPopupFollowsShell.java

@@ -0,0 +1,88 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Eclipse Platform contributors.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0 which is available at
+ * https://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package org.eclipse.jface.snippets.notifications;
+
+import org.eclipse.jface.notifications.NotificationPopup;
+import org.eclipse.swt.events.ControlAdapter;
+import org.eclipse.swt.events.ControlEvent;
+import org.eclipse.swt.events.ControlListener;
+import org.eclipse.swt.graphics.Point;
+import org.eclipse.swt.graphics.Rectangle;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Shell;
+
+/**
+ * Shows a {@link NotificationPopup} that stays anchored to the bottom-right
+ * corner of a top-level shell. Moving or resizing the shell repositions the
+ * popup, so it appears to be attached to the window.
+ */
+public class Snippet086NotificationPopupFollowsShell {
+
+	/** Same edge padding the popup uses for its initial placement. */
+	private static final int PADDING_EDGE = 5;
+
+	public static void main(String[] args) {
+		Display display = new Display();
+		Shell shell = new Shell(display);
+		shell.setText("Move or resize me"); //$NON-NLS-1$
+		shell.setSize(500, 350);
+		shell.open();
+
+		NotificationPopup popup = NotificationPopup.forShell(shell) //
+				.text("I follow the window. Drag the shell around!") //$NON-NLS-1$
+				.title("Anchored notification", true) //$NON-NLS-1$
+				.delay(0) // 0 disables the auto-close so the popup stays while you move the shell
+				.build();
+		popup.open();
+
+		Shell popupShell = popup.getShell();
+
+		// Re-anchor the popup whenever the parent shell moves or is resized.
+		ControlListener follower = new ControlAdapter() {
+			@Override
+			public void controlMoved(ControlEvent e) {
+				anchorToBottomRight(shell, popupShell);
+			}
+
+			@Override
+			public void controlResized(ControlEvent e) {
+				anchorToBottomRight(shell, popupShell);
+			}
+		};
+		shell.addControlListener(follower);
+
+		// Stop tracking once the popup is gone (e.g. closed via its close button).
+		popupShell.addDisposeListener(e -> {
+			if (!shell.isDisposed()) {
+				shell.removeControlListener(follower);
+			}
+		});
+
+		while (!shell.isDisposed()) {
+			if (!display.readAndDispatch()) {
+				display.sleep();
+			}
+		}
+
+		display.dispose();
+	}
+
+	private static void anchorToBottomRight(Shell parent, Shell popupShell) {
+		if (popupShell == null || popupShell.isDisposed()) {
+			return;
+		}
+		Rectangle clientArea = parent.getClientArea();
+		Point clientOrigin = parent.toDisplay(0, 0);
+		Point size = popupShell.getSize();
+		int x = clientOrigin.x + clientArea.width - size.x - PADDING_EDGE;
+		int y = clientOrigin.y + clientArea.height - size.y - PADDING_EDGE;
+		popupShell.setLocation(x, y);
+	}
+}