diff --git a/test/python/PikaUI/PikaUI.py b/test/python/PikaUI/PikaUI.py
index 6f7533215..203af624f 100644
--- a/test/python/PikaUI/PikaUI.py
+++ b/test/python/PikaUI/PikaUI.py
@@ -28,6 +28,7 @@ class Widget:
     align = None
     text = None
     isroot = False
+    needbuild = True
     _label = None
     _child = []
 
@@ -50,6 +51,12 @@ class Widget:
         self.parent = weakref.ref(parent)
 
     def update(self):
+        if self.needbuild:
+            built = self.build()
+            if not built is None:
+                self = self.add(built)
+            self.needbuild = False
+
         if self.parent is None:
             print('self.parent is None')
             return
@@ -96,13 +103,23 @@ class Widget:
             self._child.append(c)
         return self
 
+    def clean(self):
+        if self.backend is None:
+            return
+        if self.needbuild:
+            return
+        self.backend.clean()
+        self.needbuild = True
+        #! Memory Error
+        # self._child = []
+
 
 class Page(Widget):
     def __init__(self):
         super().__init__()
         self._setPerent(self)
         self.isroot = True
-        self.backend = _backend.Screen()
+        self.backend = _backend.screen()
 
 
 class Button(Widget):
@@ -119,22 +136,21 @@ class Text(Widget):
 
 
 class PageManager:
-    pageThis = None
+    pageThis: Page = None
     pageList = []
 
     def enter(self, page: Page):
         self.clean()
         self.pageThis = page
         self.pageList.append(page)
-        page = page.add(page.build())
         self.update()
 
     def back(self):
         if len(self.pageList) <= 1:
             return
+        self.clean()
         _ = self.pageList.pop()
         self.pageThis = self.pageList[-1]
-        self.clean()
         self.update()
 
     def update(self):
@@ -143,7 +159,9 @@ class PageManager:
         self.pageThis.update()
 
     def clean(self):
-        _backend.clean()
+        if self.pageThis is None:
+            return
+        self.pageThis.clean()
 
 
 class _App:
diff --git a/test/python/PikaUI/PikaUI_backend_text.py b/test/python/PikaUI/PikaUI_backend_text.py
index fe2141379..8f5358c80 100644
--- a/test/python/PikaUI/PikaUI_backend_text.py
+++ b/test/python/PikaUI/PikaUI_backend_text.py
@@ -20,8 +20,11 @@ class widget:
     
     def set_text(self, text):
         print('%s.set_text("%s")' % (self.name, text))
+    
+    def clean(self):
+        print("%s.clean()" % (self.name))
 
-class Screen:
+class Screen(widget):
     name = "screen"
 
 _screen = Screen(None)
@@ -31,6 +34,3 @@ class label(widget):
 
 def screen():
     return _screen
-
-def clean():
-    print('screen.clean()')
diff --git a/test/python/PikaUI/test_page.py b/test/python/PikaUI/test_page.py
index 2ab51756d..8bb0de140 100644
--- a/test/python/PikaUI/test_page.py
+++ b/test/python/PikaUI/test_page.py
@@ -1,10 +1,9 @@
 import PikaUI as ui
 from PikaStdLib import MemChecker as mem
 
-page1 = ui.Page().add(
-    ui.Text('Hello Page1')
-)
-
+class Page1(ui.Page):
+    def build(self):
+        return ui.Text('Hello Page1')
 
 class Page2(ui.Page):
     def build(self):
@@ -12,6 +11,6 @@ class Page2(ui.Page):
 
 
 app = ui.App()
-app.pageManager.enter(page1)
+app.pageManager.enter(Page1())
 app.pageManager.enter(Page2())
 app.pageManager.back()