title: Put a bitmap on top of StaticBitmap in WxPython
body: <p>I have an application that has a panel
  on which static bitmaps (wx.StaticBitmap) are placed
  in a GridBagSizer.
  I want to place a bitmap on top of certain of
  the static bitmaps, that will partly cover it and its neighbours.</p>
  <p>I've been trying like this:</p>
  <pre><code>self.panel = wx.Panel(self, -1, style=wx.TRANSPARENT_WINDOW)
  self.panel.Bind(wx.EVT_PAINT, self.place_bitmap)
  
  .
  .
  .
  
  def place_bitmap(self, *args):
      dc = wx.ClientDC(self.panel)  # or wx.PaintDC(self.panel)
  
      for xy in self.coordinates:
          dc.DrawBitmap(self.top_bitmap, xy[0], xy[1], 0)
  
      self.panel.Layout()
  </code></pre>
  <p>If I change the coordinates in <code>dc.DrawBitmap()</code>
  to a place in <code>self.panel</code> where there is no static bitmap, it shows.
  But I can't get it to show on top of the static bitmaps.
  So it seems it's getting rendered under them?</p>
  <p>How can I make the top_bitmap go on top?</p>