title: wxpython panel size and titles
body: <p>When I apply the following code, the second panel is showed over the first one. I would like to know how I can get the two panels without overlapping and with the appropriate size of the window (frame). I would also like to know if there is any suitable way to draw some kind of titles in a panel (in this case, "Inputs:" and "Outputs:"). Thanks!</p>
  
  <pre><code>import wx
  
  class Input_Panel(wx.Panel):
      def __init__(self, parent):
          wx.Panel.__init__(self, parent)
          # Input variables
          self.tittle1 = wx.StaticText(self, label="Inputs:")    
          self.lblname1 = wx.StaticText(self, label="Input 1:")
          self.format1 = ['Option 1','Option 2']
          self.combo1 = wx.ComboBox(self, size=(200, -1),value='', choices=self.format1, style=wx.CB_DROPDOWN)
          self.lblname2 = wx.StaticText(self, label="Input 2")
          self.format2 = ['Option 1','Option 2', 'Option 3']
          self.combo2 = wx.ComboBox(self, size=(200, -1),value='', choices=self.format2, style=wx.CB_DROPDOWN)
  
          # Set sizer for the panel content
          self.sizer = wx.GridBagSizer(2, 2)
          self.sizer.Add(self.tittle1, (1, 2))
          self.sizer.Add(self.lblname1, (2, 1))
          self.sizer.Add(self.combo1, (2, 2))
          self.sizer.Add(self.lblname2, (3, 1))
          self.sizer.Add(self.combo2, (3, 2))
          self.SetSizer(self.sizer)
  
  class Output_Panel(wx.Panel):
      def __init__(self, parent):
          wx.Panel.__init__(self, parent)
          # Output variables
          self.tittle2 = wx.StaticText(self, label="Outputs:")    
          self.lblname3 = wx.StaticText(self, label="Output1")
          self.result3 = wx.StaticText(self, label="", size=(100, -1))
  
          # Set sizer for the panel content
          self.sizer = wx.GridBagSizer(2, 2)
          self.sizer.Add(self.tittle2, (1, 2))
          self.sizer.Add(self.lblname3, (2, 1))
          self.sizer.Add(self.result3, (2, 2))
          self.SetSizer(self.sizer)
  
  class Main_Window(wx.Frame):
      def __init__(self, parent, title):
          wx.Frame.__init__(self, parent, title = title)
  
          # Set variable panels
          self.splitter = wx.SplitterWindow(self)
          self.panel1 = Input_Panel(self.splitter)
          self.panel2 = Output_Panel(self.splitter)
          self.splitter.SplitVertically(self.panel1, self.panel2)
  
          self.windowSizer = wx.BoxSizer(wx.VERTICAL)
          self.windowSizer.Add(self.splitter, 1, wx.ALL | wx.EXPAND)   
          self.SetSizerAndFit(self.windowSizer)
  
  def main():
      app = wx.App(False)
      frame = Main_Window(None, "App GUI")
      frame.Show()
      app.MainLoop()
  
  if __name__ == "__main__" :
      main()
  </code></pre>