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diff --git a/plugins/uml/diagram/org.eclipse.papyrus.uml.diagram.sequence/custom-src/org/eclipse/papyrus/uml/diagram/sequence/figures/FigureHitTestUtil.java b/plugins/uml/diagram/org.eclipse.papyrus.uml.diagram.sequence/custom-src/org/eclipse/papyrus/uml/diagram/sequence/figures/FigureHitTestUtil.java
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+++ b/plugins/uml/diagram/org.eclipse.papyrus.uml.diagram.sequence/custom-src/org/eclipse/papyrus/uml/diagram/sequence/figures/FigureHitTestUtil.java
@@ -0,0 +1,140 @@
+/*****************************************************************************
+ * Copyright (c) 2018 CEA LIST and others.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *   CEA LIST - Initial API and implementation
+ *
+ *****************************************************************************/
+
+package org.eclipse.papyrus.uml.diagram.sequence.figures;
+
+import java.util.List;
+
+import org.eclipse.draw2d.IFigure;
+import org.eclipse.draw2d.TreeSearch;
+import org.eclipse.draw2d.geometry.PointList;
+import org.eclipse.draw2d.geometry.Rectangle;
+
+/**
+ * Hit-test utilities for {@code IFigure figure}s.
+ */
+public class FigureHitTestUtil {
+	public static final FigureHitTestUtil INSTANCE = new FigureHitTestUtil();
+
+	private static final int FUZZ_FACTOR = 2;
+
+	// A slightly fuzzy point for hit-testing on a polyline
+	private final Rectangle fuzzyPoint = new Rectangle(0, 0,
+			FUZZ_FACTOR * 2 + 1, FUZZ_FACTOR * 2 + 1);
+
+	/**
+	 * Not instantiable by clients.
+	 */
+	private FigureHitTestUtil() {
+		super();
+	}
+
+	/**
+	 * Obtain the children of a figure as a typed list.
+	 *
+	 * @param figure
+	 *            a figure
+	 * @return its children
+	 */
+	@SuppressWarnings("unchecked")
+	public final List<? extends IFigure> getChildren(IFigure figure) {
+		return figure.getChildren();
+	}
+
+	/**
+	 * Fuzzily test whether a {@code polygon} contains some point. Effectively,
+	 * test whether the {@code polygon} overlaps a tiny square around the point.
+	 *
+	 * @param polygon
+	 *            a polygon
+	 * @param x
+	 *            the X coördinate at which to search
+	 * @param y
+	 *            the Y coördinate at which to search
+	 * @return whether the point fuzzily is in the {@code polygon}
+	 */
+	public boolean fuzzyHitTest(PointList polygon, int x, int y) {
+		boolean result = polygon.polygonContainsPoint(x, y);
+		if (!result) {
+			// If the center of our rectangle isn't in the polygon but
+			// any of it does overlap the polygon, then it must intersect
+			// the polygon boundary
+			fuzzyPoint.setLocation(x - FUZZ_FACTOR, y - FUZZ_FACTOR);
+			result = polygon.intersects(fuzzyPoint);
+		}
+		return result;
+	}
+
+	/**
+	 * Query whether any child of a {@code figure} contains a point.
+	 *
+	 * @param figure
+	 *            a figure
+	 * @param x
+	 *            the X coördinate at which to search
+	 * @param y
+	 *            the Y coördinate at which to search
+	 * @return whether any child of the {@code figure} contains the point
+	 */
+	public boolean anyChildContainsPoint(IFigure figure, int x, int y) {
+		boolean result = false;
+
+		final List<? extends IFigure> children = getChildren(figure);
+
+		for (int i = children.size() - 1; i >= 0; i--) {
+			IFigure next = children.get(i);
+			if (next.isVisible() && next.containsPoint(x, y)) {
+				result = true;
+				break;
+			}
+		}
+
+		return result;
+	}
+
+	/**
+	 * Find a child figure (recursively) at the given location, excluding
+	 * the {@code figure}, itself.
+	 *
+	 * @param figure
+	 *            a figure in which to search for some child
+	 * @param x
+	 *            the X coördinate at which to search
+	 * @param y
+	 *            the Y coördinate at which to search
+	 * @param search
+	 *            a tree search filter
+	 *
+	 * @return the child, or {@code null} if there is no child at this location
+	 */
+	public IFigure findChildAt(IFigure figure, int x, int y, TreeSearch search) {
+		IFigure result = null;
+
+		final List<? extends IFigure> children = getChildren(figure);
+
+		for (int i = children.size() - 1; i >= 0; i--) {
+			IFigure next = children.get(i);
+			if (next.isVisible()) {
+				next = next.findFigureAt(x, y, search);
+				if (next != null) {
+					result = next;
+					break;
+				}
+			}
+		}
+
+		return result;
+	}
+}