diff --git a/protege-editor-core/src/main/java/org/protege/editor/core/ui/list/MList.java b/protege-editor-core/src/main/java/org/protege/editor/core/ui/list/MList.java
index 802be98f1..e0c672a66 100644
--- a/protege-editor-core/src/main/java/org/protege/editor/core/ui/list/MList.java
+++ b/protege-editor-core/src/main/java/org/protege/editor/core/ui/list/MList.java
@@ -94,7 +94,7 @@ public void mouseMoved(MouseEvent e) {
                 handleMouseMoved();
             }
         };
-        mousePositionCache = MousePositionCache.createAndInstall(this);
+        mousePositionCache = MousePositionCache.createAndInstall(this, super::getMousePosition);
         this.addMouseMotionListener(mouseMovementListener);
         MouseListener mouseButtonListener = new MouseAdapter() {
             @Override
@@ -157,7 +157,7 @@ private void handleMouseMoved() {
         	    if (dirty != null) {        	    	  
         	    	   repaint(dirty);
         	    }
-            Point pt = getCachedMousePosition();
+            Point pt = getMousePosition();
             if (pt != null) {
                 lastMousePositionCellIndex = MList.this.locationToIndex(pt);
             }
@@ -390,7 +390,7 @@ else if (obj instanceof MListItem) {
 
     @Override
     public String getToolTipText(MouseEvent event) {
-        Point mousePos = getCachedMousePosition();
+        Point mousePos = getMousePosition();
         if (mousePos == null) {
             return null;
         }
@@ -494,7 +494,7 @@ private int paintButton(Graphics2D g2, Rectangle clipBound, int endOfButtonRun,
     }
 
     private Color getButtonColor(MListButton button) {
-        Point pt = getCachedMousePosition();
+        Point pt = getMousePosition();
         if (pt == null) {
             return button.getBackground();
         }
@@ -509,9 +509,8 @@ private Color getButtonColor(MListButton button) {
         return button.getBackground();
     }
 
-    @Nullable
-    private Point getCachedMousePosition() {
+    @Override
+    public Point getMousePosition() throws HeadlessException {
         return mousePositionCache.getMousePosition();
     }
-
 }
diff --git a/protege-editor-core/src/main/java/org/protege/editor/owl/ui/util/MousePositionCache.java b/protege-editor-core/src/main/java/org/protege/editor/owl/ui/util/MousePositionCache.java
index 9eeb5f20e..3619557e2 100644
--- a/protege-editor-core/src/main/java/org/protege/editor/owl/ui/util/MousePositionCache.java
+++ b/protege-editor-core/src/main/java/org/protege/editor/owl/ui/util/MousePositionCache.java
@@ -5,6 +5,7 @@
 import java.awt.*;
 import java.awt.event.MouseEvent;
 import java.awt.event.MouseMotionAdapter;
+import java.util.function.Supplier;
 
 import static com.google.common.base.Preconditions.checkNotNull;
 
@@ -18,21 +19,27 @@ public class MousePositionCache {
     @Nonnull
     private final Component component;
 
+    @Nonnull
+    private final Supplier<Point> mousePositionSupplier;
+
     private boolean stale = true;
 
     private Point cachedPosition = null;
 
-    private MousePositionCache(@Nonnull Component component) {
+    private MousePositionCache(@Nonnull Component component,
+                               @Nonnull Supplier<Point> mousePositionSupplier) {
         this.component = checkNotNull(component);
+        this.mousePositionSupplier = checkNotNull(mousePositionSupplier);
     }
 
-    public static MousePositionCache createAndInstall(@Nonnull Component component) {
-        MousePositionCache cache = new MousePositionCache(component);
-        cache.attacheListeners();
+    public static MousePositionCache createAndInstall(@Nonnull Component component,
+                                                      @Nonnull Supplier<Point> mousePositionSupplier) {
+        MousePositionCache cache = new MousePositionCache(component, mousePositionSupplier);
+        cache.attachListeners();
         return cache;
     }
 
-    private void attacheListeners() {
+    private void attachListeners() {
         component.addMouseMotionListener(new MouseMotionAdapter() {
             @Override
             public void mouseMoved(MouseEvent e) {
@@ -48,7 +55,7 @@ private void markAsStale() {
     @Nullable
     public Point getMousePosition() {
         if(stale) {
-            cachedPosition = component.getMousePosition();
+            cachedPosition = mousePositionSupplier.get();
             stale = false;
         }
         return cachedPosition;