public LayoutDropdownWindow(EntityManager entityManager, IEnumerable <Entity> entities)
        {
            EntityManager  = entityManager;
            Entities       = entities.ToList();
            Entity         = Entities[0];
            RectTransforms = new List <RectTransform>(Entities.Select(e => EntityManager.GetComponentData <RectTransform>(e)).ToList());
            m_Main         = RectTransforms[0];
            m_InitValues   = new Vector2[RectTransforms.Count, 4];

            for (var i = 0; i < RectTransforms.Count; ++i)
            {
                var rt = RectTransforms[i];
                m_InitValues[i, 0] = rt.anchorMin;
                m_InitValues[i, 1] = rt.anchorMax;
                m_InitValues[i, 2] = rt.anchoredPosition;
                m_InitValues[i, 3] = rt.sizeDelta;
            }
        }
        public override void OnGUI(Rect rect)
        {
            if (Event.current.type == EventType.KeyDown && Event.current.keyCode == KeyCode.Return)
            {
                editorWindow.Close();
            }

            RectTransforms.Clear();
            RectTransforms.AddRange(Entities.Select(e => EntityManager.GetComponentData <RectTransform>(e)));
            m_Main = RectTransforms[0];
            GUI.Label(new Rect(rect.x + 5, rect.y + 3, rect.width - 10, 16), EditorGUIUtility.TrTextContent("Anchor Presets"), EditorStyles.boldLabel);
            GUI.Label(new Rect(rect.x + 5, rect.y + 3 + 16, rect.width - 10, 16), EditorGUIUtility.TrTextContent("Shift: Also set pivot     Alt: Also set position"), EditorStyles.label);

            var oldColor = GUI.color;

            GUI.color = Styles.tableLineColor * oldColor;
            GUI.DrawTexture(new Rect(0, k_TopPartHeight - 1, 400, 1), EditorGUIUtility.whiteTexture);
            GUI.color = oldColor;

            GUI.BeginGroup(new Rect(rect.x, rect.y + k_TopPartHeight, rect.width, rect.height - k_TopPartHeight));
            TableGUI(rect);
            GUI.EndGroup();
        }