UnityEngine.GUILayoutUtility.Begin C# (CSharp) Method

        internal static void Begin(int instanceID)
        {
            LayoutCache cache = SelectIDList(instanceID, false);
            if (Event.current.type == EventType.Layout)
            {
                current.topLevel = cache.topLevel = new GUILayoutGroup();
                current.layoutGroups.Clear();
                current.layoutGroups.Push(current.topLevel);
                current.windows = cache.windows = new GUILayoutGroup();
            }
            else
            {
                current.topLevel = cache.topLevel;
                current.layoutGroups = cache.layoutGroups;
                current.windows = cache.windows;
            }
        }

 internal static void BeginGUI(int skinMode, int instanceID, int useGUILayout)
 {
     GUIUtility.s_SkinMode   = skinMode;
     GUIUtility.s_OriginalID = instanceID;
     GUIUtility.ResetGlobalState();
     if (useGUILayout != 0)
     {
         GUILayoutUtility.Begin(instanceID);
     }
 }