Learning wxPython, basic thing

I want to display a button that when I click adds to the main panel a static text that automatic adds to the BoxSizer of the panel. I have this code but dosen't work good. Anyone can help me? I am desperate. Thanks

import wx

class MyApp(wx.App):
    def OnInit(self):
        self.frame = MainFrame(None,title='')
        self.SetTopWindow(self.frame)
        self.frame.Show()
        return True

class MainFrame(wx.Frame):
    def __init__(self, *args, **kwargs):
        super(MainFrame, self).__init__(*args, **kwargs)

        #Atributos
        self.panel = MainPanel(self)
        self.CreateStatusBar()

        #Layout
        self.sizer = wx.BoxSizer(wx.HORIZONTAL)
        self.sizer.Add(self.panel,1,wx.EXPAND)
        self.SetSizer(self.sizer)

class 开发者_StackOverflow中文版MainPanel(wx.Panel):
    def __init__(self, parent):
        super(MainPanel, self).__init__(parent)

        #Atributos
        bmp = wx.Bitmap('./img.png',wx.BITMAP_TYPE_PNG)
        self.boton = wx.BitmapButton(self,bitmap=bmp)

        # Layout
        self.sizer = wx.BoxSizer(wx.HORIZONTAL)
        self.sizer.Add(self.boton)
        self.SetSizer(self.sizer)

        self.Bind(wx.EVT_BUTTON,self.add,self.boton)

    def add(self,event):
        self.sizer.Add(wx.StaticText(self,label='Testing'))


if __name__ == "__main__":
    app = MyApp(False)
    app.MainLoop()

If your problem is that your text initially shows up behind the button when it is clicked, you can force the sizer to update by adding a call to your Panel's Layout method.

class MainPanel(wx.Panel):
    def __init__(self, parent):
        super(MainPanel, self).__init__(parent)

        #Atributos
        bmp = wx.Bitmap('./img.png',wx.BITMAP_TYPE_PNG)
        self.boton = wx.BitmapButton(self,bitmap=bmp)

        # Layout
        self.sizer = wx.BoxSizer(wx.HORIZONTAL)
        self.sizer.Add(self.boton)
        self.SetSizer(self.sizer)

        self.Bind(wx.EVT_BUTTON,self.add,self.boton)

    def add(self,event):
        self.sizer.Add(wx.StaticText(self,label='Testing'))
        self.Layout()