diff --git a/DEV_CHANGELOG.txt b/DEV_CHANGELOG.txt
index 030981f..e231f77 100644
--- a/DEV_CHANGELOG.txt
+++ b/DEV_CHANGELOG.txt
@@ -5,3 +5,9 @@ types 모듈이 삭제되며 init.lua 에 통합됨
 이제 extend 에 대해서 Init(self) self 안에 props 기능이 내장되어있음
 
 TODO: slot 기능 구현
+
+TODO: spring 구현
+
+TODO: !ChildRemoved 구현
+
+TODO: AdvancedTween 을 submodule 로 변경
diff --git a/mock/Slot.txt b/mock/Slot.txt
new file mode 100644
index 0000000..dfc28d7
--- /dev/null
+++ b/mock/Slot.txt
@@ -0,0 +1,22 @@
+
+Window {
+  Class.Slot "Content" {
+    Text {
+      Text = "wow";
+    };
+    Text {
+      Text = "wow";
+    };
+    Text {
+      Text = "wow";
+    };
+    Text {
+      Text = "wow";
+    };
+  } 
+  TopbarButton {
+    [Class.Slot] = "Topbar";
+  };
+}
+다수가 있을경우
+이런식으로 묶을 수 있다고 하자
diff --git a/src/class.lua b/src/class.lua
index a3ff83b..1069632 100644
--- a/src/class.lua
+++ b/src/class.lua
@@ -110,8 +110,13 @@ function module.init(shared)
 	new.SetProperty = SetProperty
 
 	local function Link(linker,item,index,indexType)
-		local target = linker.target
-		local name = linker.name
+		-- error("Not implemented")
+
+		local target = linker.lvalue
+		local name = linker.key
+
+		-- local target = linker.target
+		-- local name = linker.name
 		if indexType == "number" then
 			-- set
 			-- if rawget(target,name) ~= nil then
@@ -140,7 +145,7 @@ function module.init(shared)
 		local indexType = typeof(index)
 		local quadType = valueType == "table" and PcallGetProperty(value,"__type")
 
-		if quadType == "quad_linker" then
+		if indexType == "number" and quadType == "quad_register" then
 			-- linking
 			Link(value,item,index,indexType)
 		elseif indexType == "string" and quadType == "quad_register" then
@@ -162,7 +167,8 @@ function module.init(shared)
 				local setValue,tween = value:CalcWithNewValue(item,newValue,key)
 				if tween then
 					if not advancedTween then
-						return warn "[QUAD] module 'AdvancedTween' needs to be loaded for tween properties but it is not found on 'src.libs'. you should adding that to src.libs directory"
+						warn "[QUAD] Failed to execute register handler function. (Real Instance was not updated)"
+						return warn "[QUAD] module 'AdvancedTween' needs to be loaded for tween properties but it is not found on 'src.libs'. you should adding that to src.libs directory.\nPossible reason : Cloned repository without recursive option. => 'git submodule init ; git submodule update' to get submodules"
 					end
 					-- local ended, onStepped
 					-- if tween.Ended then
@@ -349,13 +355,13 @@ function module.init(shared)
 		end
 	})
 
-	local function Linker(target,name)
-		return {
-			__type = "quad_linker";
-			target = target;
-			name = name;
-		}
-	end
+	-- local function Linker(target,name)
+	-- 	return {
+	-- 		__type = "quad_linker";
+	-- 		target = target;
+	-- 		name = name;
+	-- 	}
+	-- end
 
 	-- make class
 	function new.Extend()
@@ -400,8 +406,12 @@ function module.init(shared)
 			return self
 		end
 
-		function this:Default(...)
-			return this.__prop:Default(...)
+		-- default function from props
+		function this:Default(key,value)
+			if self == this then
+				error("prop handler not found (this method cannot be used on class)")
+			end
+			self.__prop:Default(key,value)
 		end
 
 		function this:GetPropertyChangedSignal(propertyName)
@@ -436,11 +446,18 @@ function module.init(shared)
 			thisSignal:Fire(value)
 		end
 
-		function this:GetChildren()
-			local children = rawget(self,"__child")
-			if not children then
-				return {}
+		function this:GetChildren(slotName)
+			if slotName then
+				local slot = rawget(slotName,"__slot")
+				if not slot then return {} end
+				local newSlot = {}
+				for _,v in pairs(slot) do
+					insert(newSlot,v)
+				end
+				return slot
 			end
+			local children = rawget(self,"__child")
+			if not children then return {} end
 			local newChildren = {}
 			for _,v in pairs(children) do
 				insert(newChildren,v)
@@ -504,7 +521,6 @@ function module.init(shared)
 					end
 				end
 			end
-			self = nil
 		end
 
 		--- link to new
@@ -517,7 +533,10 @@ function module.init(shared)
 			if type(name) ~= "string" then
 				error(("Name must be string, but got %s"):format(type(name)))
 			end
-			return Linker(self,name)
+			-- return Linker(self,name)
+			local register = self.__props(name)
+			register:Link(self)
+			return register
 		end
 
 		-- indexer (getter)
diff --git a/src/store.lua b/src/store.lua
index bf7101c..be9d58f 100644
--- a/src/store.lua
+++ b/src/store.lua
@@ -283,6 +283,9 @@ function module.init(shared)
 			-- return s
 			return setmetatable({avalue = avalue},{__index = s})
 		end;
+		Link = function(s,lvalue)
+			return setmetatable({avalue = lvalue},{__index = s})
+		end;
 		-- return init data
 		CalcWithDefault = function (s,withItem)
 			local with = s.wfunc