diff --git a/Assets/SEE/Controls/Actions/MarkAction.cs b/Assets/SEE/Controls/Actions/MarkAction.cs
index fabb43d535..27c735c91f 100644
--- a/Assets/SEE/Controls/Actions/MarkAction.cs
+++ b/Assets/SEE/Controls/Actions/MarkAction.cs
@@ -13,8 +13,8 @@ namespace SEE.Controls.Actions
     internal class MarkAction : AbstractPlayerAction
     {
         /// <summary>
-        /// If the user clicks with the mouse hitting a game object representing a graph node,
-        /// this graph node is a parent to which a new node is created and added as a child.
+        /// If the user clicks with the mouse hitting a game object representing a node mark,
+        /// this node mark  is a mark to which a node is created.
         /// <see cref="ReversibleAction.Update"/>.
         /// </summary>
         /// <returns>true if completed</returns>
@@ -44,14 +44,14 @@ public override bool Update()
                 }
                 else
                 {
-                    Debug.LogError($"New node could not be created.\n");
+                    Debug.LogError($"New mark could not be created.\n");
                 }
             }
             return result;
         }
 
         /// <summary>
-        /// The node that was added when this action was executed. It is saved so
+        /// The mark that was added when this action was executed. It is saved so
         /// that it can be removed on Undo().
         /// </summary>
         private GameObject addedGameMark;
@@ -105,13 +105,11 @@ public Memento(GameObject mark,int diameter ,int x,int y,string nodeid)
         }
 
         /// <summary>
-        /// Returns a scale of a square with the given center <see cref="position"/>
-        /// that fits into the ground area of <paramref name="parent"/>.
+        /// Returns a diameter of a sphere 
         /// </summary>
-        /// <param name="parent">parent in which to fit the rectangle</param>
-        /// <param name="position">center position of the rectangle</param>
-        /// <returns>the scale of a square (actually a cube, but with a very small height)
-        /// with center <see cref="position"/> that fits into the ground area of <paramref name="parent"/></returns>
+        /// <param name="x">width of the marked node</param>
+        /// <param name="y">depth of the markde node</param>
+        /// <returns>the diameter of the sphere</returns>
         private static int FindDiameter(int x, int y)
         {
             int diameter = 0;
@@ -128,7 +126,34 @@ private static int FindDiameter(int x, int y)
         }
 
         /// <summary>
-        /// Undoes this AddNodeAction.
+        /// Returns a scale of a square with the given center <see cref="position"/>
+        /// that fits into the ground area of <paramref name="parent"/>.
+        /// </summary>
+        /// <param name="parent">parent in which to fit the rectangle</param>
+        /// <param name="position">center position of the rectangle</param>
+        /// <returns>the scale of a square (actually a cube, but with a very small height)
+        /// with center <see cref="position"/> that fits into the ground area of <paramref name="parent"/></returns>
+        private static Vector3 FindSize(GameObject parent, Vector3 position)
+        {
+            // TODO: We might want to implement something smarter
+            // than that, see for instance:
+            // https://stackoverflow.com/questions/51574829/how-to-algorithmically-find-the-biggest-rectangle-that-can-fit-in-a-space-with-o
+            Vector3 result = parent.transform.lossyScale / 10;
+            // The ground area of the result must be a square.
+            if (result.x > result.z)
+            {
+                result.x = result.z;
+            }
+            else
+            {
+                result.z = result.x;
+            }
+            result.y = 0.01f;
+            return result;
+        }
+
+        /// <summary>
+        /// Undoes this MarkAction.
         /// </summary>
         public override void Undo()
         {
@@ -143,7 +168,7 @@ public override void Undo()
         }
 
         /// <summary>
-        /// Redoes this AddNodeAction.
+        /// Redoes this MarkAction.
         /// </summary>
         public override void Redo()
         {
@@ -156,7 +181,7 @@ public override void Redo()
         }
 
         /// <summary>
-        /// Returns a new instance of <see cref="AddNodeAction"/>.
+        /// Returns a new instance of <see cref="MarkAction"/>.
         /// </summary>
         /// <returns>new instance</returns>
         public static ReversibleAction CreateReversibleAction()
@@ -165,7 +190,7 @@ public static ReversibleAction CreateReversibleAction()
         }
 
         /// <summary>
-        /// Returns a new instance of <see cref="AddNodeAction"/>.
+        /// Returns a new instance of <see cref="MarkAction"/>.
         /// </summary>
         /// <returns>new instance</returns>
         public override ReversibleAction NewInstance()
@@ -176,7 +201,7 @@ public override ReversibleAction NewInstance()
         /// <summary>
         /// Returns the <see cref="ActionStateType"/> of this action.
         /// </summary>
-        /// <returns><see cref="ActionStateType.NewNode"/></returns>
+        /// <returns><see cref="ActionStateType.NewMark"/></returns>
         public override ActionStateType GetActionStateType()
         {
             return ActionStateType.NewMark;
@@ -190,7 +215,7 @@ public override HashSet<string> GetChangedObjects()
         {
             return new HashSet<string>
             {
-                memento.Parent.name,
+                memento.Mark.name,
                 memento.NodeID
             };
         }