x and ylabel problem when embedding in wx

I have problem with xlabel and ylabel when embedding in wx. See snapshot :
I put a test code which is based on dynamic_demo_wx.py, adding only the 3
lines :
        a.set_xlabel('Xaxis [u.a.]')
        a.set_ylabel('Yaxis [u.a.]')
Just to add title, and label. In this case Ylabel is superposed on ytics
labels and xlabel is hidden by the navigation toolbar.

Do I need twiking and/or understand better wxpython ?
Anyone can help me?

"sample code" :

import matplotlib
from matplotlib.backends.backend_wx import FigureCanvasWx,\
     FigureManager, NavigationToolbar2Wx

from matplotlib.figure import Figure
from matplotlib.axes import Subplot
import matplotlib.numerix as numpy
from wxPython.wx import *

TIMER_ID = wxNewId()

class PlotFigure(wxFrame):

    def __init__(self):
        wxFrame.__init__(self, None, -1, "Test embedded wxFigure")

        self.fig = Figure((6,4), 75)
        self.canvas = FigureCanvasWx(self, -1, self.fig)
        self.toolbar = NavigationToolbar2Wx(self.canvas)

        # On Windows, default frame size behaviour is incorrect
        # you don't need this under Linux
        tw, th = self.toolbar.GetSizeTuple()
        fw, fh = self.canvas.GetSizeTuple()
        self.toolbar.SetSize(wxSize(fw, th))

        # Create a figure manager to manage things
        self.figmgr = FigureManager(self.canvas, 1, self)
        # Now put all into a sizer
        sizer = wxBoxSizer(wxVERTICAL)
        # This way of adding to sizer allows resizing
        sizer.Add(self.canvas, 1, wxLEFT|wxTOP|wxGROW)
        # Best to allow the toolbar to resize!
        sizer.Add(self.toolbar, 0, wxGROW)
        EVT_TIMER(self, TIMER_ID, self.onTimer)
    def init_plot_data(self):
        a = self.fig.add_subplot(111)
        a.set_xlabel('Xaxis [u.a.]')
        a.set_ylabel('Yaxis [u.a.]')
        self.ind = numpy.arange(60)
        tmp = []
        for i in range(60):
        self.X = numpy.array(tmp)
        self.lines = a.plot(self.X[:,0],'o')
        self.count = 0

    def GetToolBar(self):
        # You will need to override GetToolBar if you are using an
        # unmanaged toolbar in your frame
        return self.toolbar
    def onTimer(self, evt):
        self.count += 1
        if self.count >= 60: self.count = 0
        self.lines[0].set_data(self.ind, self.X[:,self.count])
if __name__ == '__main__':
    app = wxPySimpleApp()
    frame = PlotFigure()
    # Initialise the timer - wxPython requires this to be connected to the
    # receivicng event handler
    t = wxTimer(frame, TIMER_ID)