Is it possible to set the size of EditorGUI.Foldout?

Hi guys, In the unity script reference EditorGUI.Foldout is shown to have a Rect parameter, both in the heading and in the example

EditorGUI.Foldout(Rect(3,3,position.width-6,15),showPosition, status);

I assume that something was changed in a recent version and the site hasn't caught up, as if I try the same thing I get the error

UnityEditor.EditorGUILayout.Foldout(bool, string, UnityEngine.GUIStyle)' has some invalid arguments`

At the moment I'm using the code below to create a grid of enemy portraits which are contained in a foldout, but if I open it other elements clip through it. Is there any way around this?

 showPosition = EditorGUILayout.Foldout(new Rect(0,0,0,0),showPosition, "Enemies");
             if(showPosition){
                 foreach (Transform child in Selection.activeGameObject.transform){
                     if (child.name == "_Enemy Settings"){
                         var enemyList = child.GetComponent<_EnemyParty>();
                         for(int cnt = 0 ; cnt < 3 ; cnt++){
                             if (enemyList.inParty[cnt] != null){
                                 if (GUI.Button(new Rect(50 * cnt, 20, 50, 50), enemyList.inParty[cnt].portrait)){
                                     
                                 }
                             }
                             else{
                                 if (GUI.Button(new Rect(50 * cnt, 20, 50, 50), "Empty")){
                                     Debug.Log("Clicked the button with an image");
                                 }
                             }
                         }
                         for(int cnt = 3 ; cnt < 6 ; cnt++){
                             if (enemyList.inParty[cnt] != null){
                                 if (GUI.Button(new Rect(50 * (cnt - 3), 70, 50, 50), enemyList.inParty[cnt].portrait)){
                                     Debug.Log("Clicked the button with an image");
                                 }
                             }
                             else{
                                 if (GUI.Button(new Rect(50 * (cnt - 3), 70, 50, 50), "Empty")){
                                     Debug.Log("Clicked the button with an image");
                                 }
                             }
                         }
                         for(int cnt = 6 ; cnt < 9 ; cnt++){
                             if (enemyList.inParty[cnt] != null){
                                 if (GUI.Button(new Rect(50 * (cnt - 6), 120, 50, 50), enemyList.inParty[cnt].portrait)){
                                     Debug.Log("Clicked the button with an image");
                                 }
                             }
                             else{
                                 if (GUI.Button(new Rect(50 * (cnt - 6), 120, 50, 50), "Empty")){
                                     Debug.Log("Clicked the button with an image");
                                 }
                             }
                         }
                     }
                 }
             }
             source = EditorGUILayout.ObjectField("My Label", source, typeof(GameObject), false) as GameObject;