diff --git a/TULIP/src/lu/list/itis/dkd/tui/space/SpatialMatrix.java b/TULIP/src/lu/list/itis/dkd/tui/space/SpatialMatrix.java
index bc4104645586c590f7915a29d6d4184a1030e798..e84a9624ae6ba48dd0c5c51317af30b88f2abb7b 100644
--- a/TULIP/src/lu/list/itis/dkd/tui/space/SpatialMatrix.java
+++ b/TULIP/src/lu/list/itis/dkd/tui/space/SpatialMatrix.java
@@ -59,8 +59,8 @@ public class SpatialMatrix {
      *        The object to add.
      */
     public synchronized void add(TangibleObject object) {
-        horizontal.add(findHorizontalIndexFor(object), object);
-        vertical.add(findVerticalIndexFor(object), object);
+        horizontal.add(findHorizontalIndexFor(object, false), object);
+        vertical.add(findVerticalIndexFor(object, false), object);
     }
 
     /**
@@ -113,10 +113,18 @@ public class SpatialMatrix {
      * @return The index to add the element or the size of the list if the element should be added
      *         at the end.
      */
-    private synchronized int findHorizontalIndexFor(TangibleObject object) {
+    private synchronized int findHorizontalIndexFor(TangibleObject object, boolean strict) {
         for (int index = 0; index < horizontal.size(); index++) {
-            if (Double.compare(object.getPosition().toScreenCoordinates().getX(), horizontal.get(index).getPosition().toScreenCoordinates().getX()) <= 0) {
-                return index;
+            int comparisonResult = Double.compare(object.getPosition().toScreenCoordinates().getX(), horizontal.get(index).getPosition().toScreenCoordinates().getX());
+
+            if (strict) {
+                if (comparisonResult < 0) {
+                    return index;
+                }
+            } else {
+                if (comparisonResult <= 0) {
+                    return index;
+                }
             }
         }
         return horizontal.size();
@@ -132,12 +140,20 @@ public class SpatialMatrix {
      * @return The index to add the element or the size of the list if the element should be added
      *         at the end.
      */
-    private synchronized int findHorizontalIndexFor(int objectId) {
+    private synchronized int findHorizontalIndexFor(int objectId, boolean strict) {
         BaseWidget widget = TangibleObjectManager.getWidget(objectId);
 
         for (int index = 0; index < horizontal.size(); index++) {
-            if (Double.compare(widget.getPosition(objectId).toScreenCoordinates().getX(), horizontal.get(index).getPosition().toScreenCoordinates().getX()) <= 0) {
-                return index;
+            int comparisonResult = Double.compare(widget.getPosition(objectId).toScreenCoordinates().getX(), horizontal.get(index).getPosition().toScreenCoordinates().getX());
+
+            if (strict) {
+                if (comparisonResult < 0) {
+                    return index;
+                }
+            } else {
+                if (comparisonResult <= 0) {
+                    return index;
+                }
             }
         }
         return horizontal.size();
@@ -154,10 +170,17 @@ public class SpatialMatrix {
      * @return The index to add the element or the size of the list if the element should be added
      *         at the end.
      */
-    private synchronized int findVerticalIndexFor(TangibleObject object) {
+    private synchronized int findVerticalIndexFor(TangibleObject object, boolean strict) {
         for (int index = 0; index < vertical.size(); index++) {
-            if (Double.compare(object.getPosition().toScreenCoordinates().getY(), vertical.get(index).getPosition().toScreenCoordinates().getY()) <= 0) {
-                return index;
+            int comparisonResult = Double.compare(object.getPosition().toScreenCoordinates().getY(), vertical.get(index).getPosition().toScreenCoordinates().getY());
+            if (strict) {
+                if (comparisonResult < 0) {
+                    return index;
+                }
+            } else {
+                if (comparisonResult <= 0) {
+                    return index;
+                }
             }
         }
         return vertical.size();
@@ -173,12 +196,20 @@ public class SpatialMatrix {
      * @return The index to add the element or the size of the list if the element should be added
      *         at the end.
      */
-    private synchronized int findVerticalIndexFor(int objectId) {
+    private synchronized int findVerticalIndexFor(int objectId, boolean strict) {
         BaseWidget widget = TangibleObjectManager.getWidget(objectId);
 
         for (int index = 0; index < vertical.size(); index++) {
-            if (Double.compare(widget.getPosition(objectId).toScreenCoordinates().getY(), vertical.get(index).getPosition().toScreenCoordinates().getY()) <= 0) {
-                return index;
+            int comparisonResult = Double.compare(widget.getPosition(objectId).toScreenCoordinates().getY(), vertical.get(index).getPosition().toScreenCoordinates().getY());
+
+            if (strict) {
+                if (comparisonResult < 0) {
+                    return index;
+                }
+            } else {
+                if (comparisonResult <= 0) {
+                    return index;
+                }
             }
         }
         return vertical.size();
@@ -200,7 +231,7 @@ public class SpatialMatrix {
      *         left of the given object.
      */
     public synchronized List<TangibleObject> leftOf(int objectId) {
-        int index = findHorizontalIndexFor(objectId);
+        int index = findHorizontalIndexFor(objectId, false);
         return new ArrayList<>(horizontal.subList(0, index));
     }
 
@@ -220,7 +251,7 @@ public class SpatialMatrix {
      *         right of the given object.
      */
     public synchronized List<TangibleObject> rightOf(int objectId) {
-        int index = findHorizontalIndexFor(objectId) + 1;
+        int index = findHorizontalIndexFor(objectId, true);
         return new ArrayList<>(horizontal.subList(index, horizontal.size()));
     }
 
@@ -240,7 +271,7 @@ public class SpatialMatrix {
      *         above the given object.
      */
     public synchronized List<TangibleObject> above(int objectId) {
-        int index = findVerticalIndexFor(objectId);
+        int index = findVerticalIndexFor(objectId, false);
         return new ArrayList<>(vertical.subList(0, index));
     }
 
@@ -260,7 +291,7 @@ public class SpatialMatrix {
      *         the given object.
      */
     public synchronized List<TangibleObject> below(int objectId) {
-        int index = findVerticalIndexFor(objectId) + 1;
+        int index = findVerticalIndexFor(objectId, true);
         return new ArrayList<>(vertical.subList(index, vertical.size()));
     }