diff --git a/Assets/IsoTools/Examples/Scenes/Scene11.unity b/Assets/IsoTools/Examples/Scenes/Scene11.unity
index 2543475..30e62e4 100644
--- a/Assets/IsoTools/Examples/Scenes/Scene11.unity
+++ b/Assets/IsoTools/Examples/Scenes/Scene11.unity
@@ -108,7 +108,7 @@ Prefab:
       objectReference: {fileID: 0}
     - target: {fileID: 417424, guid: 185575a05f87743c0b2ddb83dd39c6cd, type: 2}
       propertyPath: m_LocalPosition.z
-      value: 1
+      value: 1.2
       objectReference: {fileID: 0}
     - target: {fileID: 417424, guid: 185575a05f87743c0b2ddb83dd39c6cd, type: 2}
       propertyPath: m_LocalRotation.x
@@ -240,9 +240,11 @@ MonoBehaviour:
   _startDepth: 1
   _showIsoBounds: 0
   _showScreenBounds: 0
-  _showDepends: 1
   _snapByCells: 1
   _snapByObjects: 1
+  _showDepends: 1
+  _showQuadTree: 0
+  _showScreenGrid: 0
 --- !u!1001 &769235453
 Prefab:
   m_ObjectHideFlags: 0
@@ -424,7 +426,7 @@ Prefab:
       objectReference: {fileID: 0}
     - target: {fileID: 417424, guid: 185575a05f87743c0b2ddb83dd39c6cd, type: 2}
       propertyPath: m_LocalPosition.z
-      value: 1.2
+      value: 1
       objectReference: {fileID: 0}
     - target: {fileID: 417424, guid: 185575a05f87743c0b2ddb83dd39c6cd, type: 2}
       propertyPath: m_LocalRotation.x
diff --git a/Assets/IsoTools/Scripts/Internal/IsoGrid.cs b/Assets/IsoTools/Scripts/Internal/IsoGrid.cs
index 48e8702..db9745a 100644
--- a/Assets/IsoTools/Scripts/Internal/IsoGrid.cs
+++ b/Assets/IsoTools/Scripts/Internal/IsoGrid.cs
@@ -15,7 +15,11 @@ namespace IsoTools.Internal {
 			void    GetMinMaxCells (T item, ref IsoPoint2 min, ref IsoPoint2 max);
 		}
 
-		public interface ILookUpper {
+		public interface IBoundsLookUpper {
+			void LookUp(IsoRect bounds);
+		}
+
+		public interface IContentLookUpper {
 			void LookUp(IsoList<T> items);
 		}
 
@@ -109,13 +113,35 @@ namespace IsoTools.Internal {
 			_gridNumPosCount = IsoPoint2.zero;
 		}
 
-		public void LookUpCells(
-			IsoPoint2 min_cell, IsoPoint2 max_cell, ILookUpper look_upper)
+		public void VisitAllBounds(IBoundsLookUpper look_upper) {
+			if ( look_upper == null ) {
+				throw new System.ArgumentNullException("look_upper");
+			}
+			for ( int y = 0, ye = _gridNumPosCount.y; y < ye; ++y ) {
+			for ( int x = 0, xe = _gridNumPosCount.x; x < xe; ++x ) {
+				var cell = GetCell(x, y);
+				if ( cell.Items.Count > 0 ) {
+					var rect = new IsoRect(
+						x * _gridCellSize,
+						y * _gridCellSize,
+						x * _gridCellSize + _gridCellSize,
+						y * _gridCellSize + _gridCellSize);
+					rect.Translate(
+						_gridMinNumPos.x * _gridCellSize,
+						_gridMinNumPos.y * _gridCellSize);
+					look_upper.LookUp(rect);
+				}
+			}}
+		}
+
+		public void VisitItemsByCells(
+			IsoPoint2 min_cell, IsoPoint2 max_cell,
+			IContentLookUpper look_upper)
 		{
 			if ( min_cell.x < 0 || min_cell.y < 0 ) {
 				throw new System.ArgumentOutOfRangeException("min_cell");
 			}
-			if ( min_cell.y >= _gridNumPosCount.x || min_cell.y >= _gridNumPosCount.y ) {
+			if ( max_cell.x > _gridNumPosCount.x || max_cell.y > _gridNumPosCount.y ) {
 				throw new System.ArgumentOutOfRangeException("max_cell");
 			}
 			if ( look_upper == null ) {
diff --git a/Assets/IsoTools/Scripts/Internal/IsoQuadTree.cs b/Assets/IsoTools/Scripts/Internal/IsoQuadTree.cs
index 875d960..5549906 100644
--- a/Assets/IsoTools/Scripts/Internal/IsoQuadTree.cs
+++ b/Assets/IsoTools/Scripts/Internal/IsoQuadTree.cs
@@ -19,39 +19,7 @@ namespace IsoTools.Internal {
 
 		// ---------------------------------------------------------------------
 		//
-		// ItemPool
-		//
-		// ---------------------------------------------------------------------
-
-		class Item {
-			public Node    Owner   = null;
-			public IsoRect Bounds  = IsoRect.zero;
-			public T       Content = default(T);
-
-			public Item Init(Node owner, IsoRect bounds, T content) {
-				Owner   = owner;
-				Bounds  = bounds;
-				Content = content;
-				return this;
-			}
-
-			public Item Clear() {
-				return Init(null, IsoRect.zero, default(T));
-			}
-		}
-
-		class ItemPool : IsoPool<Item> {
-			public ItemPool(int capacity) : base(capacity) {
-			}
-
-			public override Item CreateItem() {
-				return new Item();
-			}
-		}
-
-		// ---------------------------------------------------------------------
-		//
-		// NodePool
+		// Node
 		//
 		// ---------------------------------------------------------------------
 
@@ -61,26 +29,47 @@ namespace IsoTools.Internal {
 			public Node[]             Nodes      = new Node[4];
 			public IsoAssocList<Item> Items      = new IsoAssocList<Item>(MinChildCountPerNode);
 			public Node               Parent     = null;
-			public IsoRect            Bounds     = IsoRect.zero;
+			public IsoRect            SelfBounds = IsoRect.zero;
 			public IsoRect[]          NodeBounds = new IsoRect[4];
 
 			public Node Init(Node parent, IsoRect bounds) {
-				Parent = parent;
-				Bounds = bounds;
+				Parent     = parent;
+				SelfBounds = bounds;
 				return FillNodeBounds();
 			}
 
-			public Node Clear(IsoIPool<Node> node_pool, IsoIPool<Item> item_pool) {
+			public Node Clear(
+				IsoIPool<Node> node_pool, IsoIPool<Item> item_pool)
+			{
 				ClearNodes(node_pool, item_pool);
 				ClearItems(item_pool);
 				return Init(null, IsoRect.zero);
 			}
 
+			public bool CleanUpNodes(
+				IsoIPool<Node> node_pool, IsoIPool<Item> item_pool)
+			{
+				var has_any_busy_nodes = false;
+				for ( int i = 0, e = Nodes.Length; i < e; ++i ) {
+					var node = Nodes[i];
+					if ( node != null ) {
+						if ( node.CleanUpNodes(node_pool, item_pool) ) {
+							node_pool.Release(
+								node.Clear(node_pool, item_pool));
+							Nodes[i] = null;
+						} else {
+							has_any_busy_nodes = true;
+						}
+					}
+				}
+				return !has_any_busy_nodes && Items.Count == 0;
+			}
+
 			public bool AddItem(
 				IsoRect bounds, T content, out Item item,
 				IsoIPool<Node> node_pool, IsoIPool<Item> item_pool)
 			{
-				if ( !Bounds.Contains(bounds) ) {
+				if ( !SelfBounds.Contains(bounds) ) {
 					item = null;
 					return false;
 				}
@@ -112,12 +101,14 @@ namespace IsoTools.Internal {
 				return true;
 			}
 
-			public void RemoveItem(Item item) {
-				Items.Remove(item);
+			public void RemoveItem(Item item, IsoIPool<Item> item_pool) {
+				if ( Items.Remove(item) ) {
+					item_pool.Release(item.Clear());
+				}
 			}
 
 			public void VisitAllBounds(IBoundsLookUpper look_upper) {
-				look_upper.LookUp(Bounds);
+				look_upper.LookUp(SelfBounds);
 				for ( int i = 0, e = Nodes.Length; i < e; ++i ) {
 					if ( Nodes[i] != null ) {
 						Nodes[i].VisitAllBounds(look_upper);
@@ -125,8 +116,10 @@ namespace IsoTools.Internal {
 				}
 			}
 
-			public void VisitItemsByBounds(IsoRect bounds, IContentLookUpper look_upper) {
-				if ( Bounds.Overlaps(bounds) ) {
+			public void VisitItemsByBounds(
+				IsoRect bounds, IContentLookUpper look_upper)
+			{
+				if ( bounds.Overlaps(SelfBounds) ) {
 					for ( int i = 0, e = Items.Count; i < e; ++i ) {
 						var item = Items[i];
 						if ( bounds.Overlaps(item.Bounds) ) {
@@ -147,8 +140,8 @@ namespace IsoTools.Internal {
 			//
 
 			Node FillNodeBounds() {
-				var size   = Bounds.size * 0.5f;
-				var center = Bounds.center;
+				var size   = SelfBounds.size * 0.5f;
+				var center = SelfBounds.center;
 				{ // LT
 					var rect = new IsoRect(center - size, center);
 					NodeBounds[0] = rect;
@@ -174,8 +167,7 @@ namespace IsoTools.Internal {
 				for ( int i = 0, e = Nodes.Length; i < e; ++i ) {
 					var node = Nodes[i];
 					if ( node != null ) {
-						node_pool.Release(
-							node.Clear(node_pool, item_pool));
+						node_pool.Release(node.Clear(node_pool, item_pool));
 					}
 				}
 				System.Array.Clear(Nodes, 0, Nodes.Length);
@@ -184,13 +176,41 @@ namespace IsoTools.Internal {
 			void ClearItems(IsoIPool<Item> item_pool) {
 				for ( int i = 0, e = Items.Count; i < e; ++i ) {
 					var item = Items[i];
-					item_pool.Release(
-						item.Clear());
+					item_pool.Release(item.Clear());
 				}
 				Items.Clear();
 			}
 		}
 
+		// ---------------------------------------------------------------------
+		//
+		// Item
+		//
+		// ---------------------------------------------------------------------
+
+		class Item {
+			public Node    Owner   = null;
+			public IsoRect Bounds  = IsoRect.zero;
+			public T       Content = default(T);
+
+			public Item Init(Node owner, IsoRect bounds, T content) {
+				Owner   = owner;
+				Bounds  = bounds;
+				Content = content;
+				return this;
+			}
+
+			public Item Clear() {
+				return Init(null, IsoRect.zero, default(T));
+			}
+		}
+
+		// ---------------------------------------------------------------------
+		//
+		// Pools
+		//
+		// ---------------------------------------------------------------------
+
 		class NodePool : IsoPool<Node> {
 			public NodePool(int capacity) : base(capacity) {
 			}
@@ -200,6 +220,15 @@ namespace IsoTools.Internal {
 			}
 		}
 
+		class ItemPool : IsoPool<Item> {
+			public ItemPool(int capacity) : base(capacity) {
+			}
+
+			public override Item CreateItem() {
+				return new Item();
+			}
+		}
+
 		// ---------------------------------------------------------------------
 		//
 		// Members
@@ -225,44 +254,67 @@ namespace IsoTools.Internal {
 		}
 
 		public void AddItem(IsoRect bounds, T content) {
-			if ( bounds.x.size > 0.0f && bounds.y.size > 0.0f ) {
-				if ( _allItems.ContainsKey(content) ) {
-					MoveItem(bounds, content);
-				} else {
-					if ( _rootNode == null ) {
-						var initial_bounds = new IsoRect(
-							bounds.center - bounds.size * 2.0f,
-							bounds.center + bounds.size * 2.0f);
-						_rootNode = _nodePool.Take().Init(null, initial_bounds);
-					}
-					Item item;
-					while ( !_rootNode.AddItem(bounds, content, out item, _nodePool, _itemPool) ) {
-						GrowUp(
-							bounds.center.x < _rootNode.Bounds.center.x,
-							bounds.center.y < _rootNode.Bounds.center.y);
-					}
-					_allItems.Add(content, item);
+			if ( _allItems.ContainsKey(content) ) {
+				MoveItem(bounds, content);
+			} else if ( bounds.x.size > 0.0f && bounds.y.size > 0.0f ) {
+				if ( _rootNode == null ) {
+					var initial_side = IsoUtils.Vec2From(
+						IsoUtils.Vec2MaxF(bounds.size));
+					var initial_bounds = new IsoRect(
+						bounds.center - initial_side * 2.0f,
+						bounds.center + initial_side * 2.0f);
+					_rootNode = _nodePool.Take().Init(null, initial_bounds);
 				}
+				Item item;
+				while ( !_rootNode.AddItem(bounds, content, out item, _nodePool, _itemPool) ) {
+					GrowUp(
+						bounds.center.x < _rootNode.SelfBounds.center.x,
+						bounds.center.y < _rootNode.SelfBounds.center.y);
+				}
+				_allItems.Add(content, item);
+				_rootNode.CleanUpNodes(_nodePool, _itemPool);
 			}
 		}
 
-		public bool RemoveItem(T content) {
+		public void RemoveItem(T content) {
 			Item item;
 			if ( _allItems.TryGetValue(content, out item) ) {
-				if ( item.Owner != null ) {
-					item.Owner.RemoveItem(item);
-				}
 				_allItems.Remove(content);
-				return true;
-			} else {
-				return false;
+				var item_node = item.Owner;
+				item_node.RemoveItem(item, _itemPool);
+				if ( item_node.Items.Count == 0 ) {
+					BackwardNodeCleanUp(item_node);
+				}
 			}
 		}
 
 		public void MoveItem(IsoRect bounds, T content) {
-			//TODO implme
-			RemoveItem(content);
-			AddItem(bounds, content);
+			Item item;
+			if ( _allItems.TryGetValue(content, out item) ) {
+				var item_node = item.Owner;
+				if ( item_node.SelfBounds.Contains(bounds) && item_node.Items.Count <= MinChildCountPerNode ) {
+					item.Bounds = bounds;
+				} else {
+					item_node.RemoveItem(item, _itemPool);
+					if ( item_node.Items.Count == 0 ) {
+						item_node = BackwardNodeCleanUp(item_node) ?? _rootNode;
+					}
+					while ( item_node != null ) {
+						Item new_item;
+						if ( item_node.SelfBounds.Contains(bounds) ) {
+							if ( item_node.AddItem(bounds, content, out new_item, _nodePool, _itemPool) ) {
+								_allItems[content] = new_item;
+								return;
+							}
+						}
+						item_node = item_node.Parent;
+					}
+					_allItems.Remove(content);
+					AddItem(bounds, content);
+				}
+			} else {
+				AddItem(bounds, content);
+			}
 		}
 
 		public void Clear() {
@@ -299,11 +351,11 @@ namespace IsoTools.Internal {
 		// ---------------------------------------------------------------------
 
 		void GrowUp(bool left, bool top) {
-			var new_root_bounds = _rootNode.Bounds;
+			var new_root_bounds = _rootNode.SelfBounds;
 			new_root_bounds.Translate(
-				left ? -_rootNode.Bounds.size.x : 0.0f,
-				top  ? -_rootNode.Bounds.size.y : 0.0f);
-			new_root_bounds.Resize(_rootNode.Bounds.size * 2.0f);
+				left ? -new_root_bounds.size.x : 0.0f,
+				top  ? -new_root_bounds.size.y : 0.0f);
+			new_root_bounds.Resize(new_root_bounds.size * 2.0f);
 			var new_root = _nodePool.Take().Init(null, new_root_bounds);
 			if ( left ) {
 				if ( top ) {
@@ -321,5 +373,12 @@ namespace IsoTools.Internal {
 			_rootNode.Parent = new_root;
 			_rootNode = new_root;
 		}
+
+		Node BackwardNodeCleanUp(Node node) {
+			while ( node != null && node.CleanUpNodes(_nodePool, _itemPool) ) {
+				node = node.Parent;
+			}
+			return node;
+		}
 	}
 }
\ No newline at end of file
diff --git a/Assets/IsoTools/Scripts/Internal/IsoScreenSolver.cs b/Assets/IsoTools/Scripts/Internal/IsoScreenSolver.cs
index 0e6cf54..1a46794 100644
--- a/Assets/IsoTools/Scripts/Internal/IsoScreenSolver.cs
+++ b/Assets/IsoTools/Scripts/Internal/IsoScreenSolver.cs
@@ -7,16 +7,18 @@ using UnityEngine.Profiling;
 
 namespace IsoTools.Internal {
 	public class IsoScreenSolver {
-		Vector2                 _minIsoXY     = Vector2.zero;
-		IsoAssocList<IsoObject> _oldVisibles  = new IsoAssocList<IsoObject>();
-		IsoAssocList<IsoObject> _curVisibles  = new IsoAssocList<IsoObject>();
+		Vector2                 _minIsoXY    = Vector2.zero;
+		IsoAssocList<IsoObject> _oldVisibles = new IsoAssocList<IsoObject>();
+		IsoAssocList<IsoObject> _curVisibles = new IsoAssocList<IsoObject>();
 
-		IsoQuadTree<IsoObject>  _quadTree     = new IsoQuadTree<IsoObject>(47);
-		IsoGrid<IsoObject>      _screenGrid   = new IsoGrid<IsoObject>(new IsoGridItemAdapter(), 47);
+		IsoQuadTree<IsoObject>  _quadTree    = new IsoQuadTree<IsoObject>(47);
+		IsoGrid<IsoObject>      _screenGrid  = new IsoGrid<IsoObject>(new IsoSGItemAdapter(), 47);
 
-		IsoQTBoundsLookUpper    _qtBoundsLU   = new IsoQTBoundsLookUpper();
-		IsoQTContentLookUpper   _qtContentLU  = new IsoQTContentLookUpper();
-		IsoGridLookUpper        _screenGridLU = new IsoGridLookUpper();
+		IsoQTBoundsLookUpper    _qtBoundsLU  = new IsoQTBoundsLookUpper();
+		IsoQTContentLookUpper   _qtContentLU = new IsoQTContentLookUpper();
+
+		IsoSGBoundsLookUpper    _sgBoundsLU  = new IsoSGBoundsLookUpper();
+		IsoSGContentLookUpper   _sgContentLU = new IsoSGContentLookUpper();
 
 		// ---------------------------------------------------------------------
 		//
@@ -27,7 +29,10 @@ namespace IsoTools.Internal {
 		class IsoQTBoundsLookUpper : IsoQuadTree<IsoObject>.IBoundsLookUpper {
 			public void LookUp(IsoRect bounds) {
 			#if UNITY_EDITOR
-				IsoUtils.DrawRect(bounds, Color.blue);
+				IsoUtils.DrawSolidRect(
+					bounds,
+					IsoUtils.ColorChangeA(Color.red, 0.05f),
+					Color.red);
 			#endif
 			}
 		}
@@ -64,11 +69,11 @@ namespace IsoTools.Internal {
 
 		// ---------------------------------------------------------------------
 		//
-		// IsoGridItemAdapter
+		// IsoSGItemAdapter
 		//
 		// ---------------------------------------------------------------------
 
-		class IsoGridItemAdapter : IsoGrid<IsoObject>.IItemAdapter {
+		class IsoSGItemAdapter : IsoGrid<IsoObject>.IItemAdapter {
 			public IsoRect GetBounds(IsoObject item) {
 				return item.Internal.ScreenBounds;
 			}
@@ -86,11 +91,28 @@ namespace IsoTools.Internal {
 
 		// ---------------------------------------------------------------------
 		//
-		// IsoGridLookUpper
+		// IsoSGBoundsLookUpper
 		//
 		// ---------------------------------------------------------------------
 
-		class IsoGridLookUpper : IsoGrid<IsoObject>.ILookUpper {
+		class IsoSGBoundsLookUpper : IsoGrid<IsoObject>.IBoundsLookUpper {
+			public void LookUp(IsoRect bounds) {
+			#if UNITY_EDITOR
+				IsoUtils.DrawSolidRect(
+					bounds,
+					IsoUtils.ColorChangeA(Color.green, 0.1f),
+					Color.green);
+			#endif
+			}
+		}
+
+		// ---------------------------------------------------------------------
+		//
+		// IsoSGContentLookUpper
+		//
+		// ---------------------------------------------------------------------
+
+		class IsoSGContentLookUpper : IsoGrid<IsoObject>.IContentLookUpper {
 			IsoObject _isoObject;
 
 			public void LookUp(IsoList<IsoObject> items) {
@@ -102,7 +124,7 @@ namespace IsoTools.Internal {
 				IsoScreenSolver screen_solver, IsoObject iso_object)
 			{
 				_isoObject = iso_object;
-				screen_solver._screenGrid.LookUpCells(
+				screen_solver._screenGrid.VisitItemsByCells(
 					iso_object.Internal.MinGridCell,
 					iso_object.Internal.MaxGridCell,
 					this);
@@ -138,6 +160,7 @@ namespace IsoTools.Internal {
 			_quadTree.AddItem(
 				iso_object.Internal.ScreenBounds,
 				iso_object);
+			_minIsoXY = IsoUtils.Vec2Min(_minIsoXY, iso_object.position);
 		}
 
 		public void OnRemoveInstance(IsoObject iso_object) {
@@ -151,6 +174,7 @@ namespace IsoTools.Internal {
 			_quadTree.MoveItem(
 				iso_object.Internal.ScreenBounds,
 				iso_object);
+			_minIsoXY = IsoUtils.Vec2Min(_minIsoXY, iso_object.position);
 			if ( !iso_object.Internal.Dirty && _curVisibles.Contains(iso_object) ) {
 				iso_object.Internal.Dirty = true;
 				return true;
@@ -160,21 +184,12 @@ namespace IsoTools.Internal {
 
 	#if UNITY_EDITOR
 		public void OnDrawGizmos(IsoWorld iso_world) {
-			_quadTree.VisitAllBounds(_qtBoundsLU);
-			/*
-			for ( int y = 0, ye = (int)_sectorsNumPosCount.y; y < ye; ++y ) {
-			for ( int x = 0, xe = (int)_sectorsNumPosCount.x; x < xe; ++x ) {
-				var sector = FindSector((float)x, (float)y);
-				if ( sector != null && sector.objects.Count > 0 ) {
-					var rect = new IsoRect(
-						(x * _sectorsSize),
-						(y * _sectorsSize),
-						(x * _sectorsSize) + _sectorsSize,
-						(y * _sectorsSize) + _sectorsSize);
-					rect.Translate(_sectorsMinNumPos * _sectorsSize);
-					IsoUtils.DrawRect(rect, Color.blue);
-				}
-			}}*/
+			if ( iso_world.isShowQuadTree ) {
+				_quadTree.VisitAllBounds(_qtBoundsLU);
+			}
+			if ( iso_world.isShowScreenGrid ) {
+				_screenGrid.VisitAllBounds(_sgBoundsLU);
+			}
 		}
 	#endif
 
@@ -205,7 +220,7 @@ namespace IsoTools.Internal {
 
 		public void SetupIsoObjectDepends(IsoObject iso_object) {
 			ClearIsoObjectDepends(iso_object);
-			_screenGridLU.LookUpForDepends(this, iso_object);
+			_sgContentLU.LookUpForDepends(this, iso_object);
 		}
 
 		public void ClearIsoObjectDepends(IsoObject iso_object) {
@@ -237,16 +252,8 @@ namespace IsoTools.Internal {
 
 		void ProcessAllInstances(IsoAssocList<IsoObject> instances) {
 			if ( instances.Count > 0 ) {
-				_minIsoXY.Set(float.MaxValue, float.MaxValue);
 				for ( int i = 0, e = instances.Count; i < e; ++i ) {
 					var iso_object = instances[i];
-					var object_pos = iso_object.position;
-					if ( _minIsoXY.x > object_pos.x ) {
-						_minIsoXY.x = object_pos.x;
-					}
-					if ( _minIsoXY.y > object_pos.y ) {
-						_minIsoXY.y = object_pos.y;
-					}
 					if ( !IsoUtils.Vec2Approximately(
 						iso_object.Internal.LastTrans,
 						iso_object.Internal.Transform.position) )
@@ -254,8 +261,6 @@ namespace IsoTools.Internal {
 						iso_object.FixIsoPosition();
 					}
 				}
-			} else {
-				_minIsoXY.Set(0.0f, 0.0f);
 			}
 		}
 
diff --git a/Assets/IsoTools/Scripts/Internal/IsoUtils.cs b/Assets/IsoTools/Scripts/Internal/IsoUtils.cs
index 55e504a..aa79e31 100644
--- a/Assets/IsoTools/Scripts/Internal/IsoUtils.cs
+++ b/Assets/IsoTools/Scripts/Internal/IsoUtils.cs
@@ -542,6 +542,13 @@ namespace IsoTools.Internal {
 			Handles.DrawLine(point2, point3);
 			Handles.DrawLine(point3, point0);
 		}
+
+		public static void DrawSolidRect(IsoRect rect, Color face_color, Color outline_color) {
+			Handles.DrawSolidRectangleWithOutline(
+				new Rect(rect.x.min, rect.y.min, rect.size.x, rect.size.y),
+				face_color,
+				outline_color);
+		}
 	#endif
 	}
 }
\ No newline at end of file
diff --git a/Assets/IsoTools/Scripts/IsoWorld.cs b/Assets/IsoTools/Scripts/IsoWorld.cs
index b7af7ed..98c481e 100644
--- a/Assets/IsoTools/Scripts/IsoWorld.cs
+++ b/Assets/IsoTools/Scripts/IsoWorld.cs
@@ -297,11 +297,6 @@ namespace IsoTools {
 			get { return _showScreenBounds; }
 			set { _showScreenBounds = value; }
 		}
-		[SerializeField] bool _showDepends = false;
-		public bool isShowDepends {
-			get { return _showDepends; }
-			set { _showDepends = value; }
-		}
 		[SerializeField] bool _snapByCells = true;
 		public bool isSnapByCells {
 			get { return _snapByCells; }
@@ -312,6 +307,22 @@ namespace IsoTools {
 			get { return _snapByObjects; }
 			set { _snapByObjects = value; }
 		}
+		[Header("Development Only")]
+		[SerializeField] bool _showDepends = false;
+		public bool isShowDepends {
+			get { return _showDepends; }
+			set { _showDepends = value; }
+		}
+		[SerializeField] bool _showQuadTree = false;
+		public bool isShowQuadTree {
+			get { return _showQuadTree; }
+			set { _showQuadTree = value; }
+		}
+		[SerializeField] bool _showScreenGrid = false;
+		public bool isShowScreenGrid {
+			get { return _showScreenGrid; }
+			set { _showScreenGrid = value; }
+		}
 	#endif
 
 		// ---------------------------------------------------------------------
@@ -441,17 +452,6 @@ namespace IsoTools {
 			_screenSolver.OnDrawGizmos(this);
 			_sortingSolver.OnDrawGizmos();
 		}
-
-		/* QuadTree WIP
-		void OnDrawGizmos() {
-			var qt = new IsoQuadTree<IsoObject>(_objects.Count);
-			for ( int i = 0, e = _objects.Count; i < e; ++i ) {
-				qt.Insert(_objects[i].Internal.ScreenRect, _objects[i]);
-			}
-			qt.VisitAllBounds(rect => {
-				IsoUtils.DrawRect(rect, Color.green);
-			});
-		}*/
 	#endif
 	}
 }
\ No newline at end of file