大侠请留步！wxpython：为啥使用aui后控件原本的pos、size没起作用

大侠请留步！！！wxpython：为何使用aui后控件原本的pos、size没起作用？
为何使用aui后控件原本的pos、size貌似没起作用，怎样才能让它们起作用啊？

Python code

import wximport wx.auiclass MyFrame(wx.Frame):    def __init__(self):        wx.Frame.__init__(self, None, -1, "test",            pos=wx.DefaultPosition,size = (600,400))                self.mgr = wx.aui.AuiManager(self)        a1 = wx.Panel(self, -1, (0,0), (200,400))        a2 = wx.Panel(self, -1, (200,0),(400,50))        a3 = wx.Panel(self, -1, (200,50),(400,350))        self.mgr.AddPane(a1, wx.aui.AuiPaneInfo().Left())        self.mgr.AddPane(a2, wx.aui.AuiPaneInfo().Center())        self.mgr.AddPane(a3, wx.aui.AuiPaneInfo().Center())        self.mgr.Update()class MyApp(wx.App):    def OnInit(self):        frame = MyFrame()        frame.Show()        self.SetTopWindow(frame)        return 1app = MyApp(0)app.MainLoop()