Why should I make multiple wx.Panel's?

Question

Following this tutorial on WxPython, I've noticed that in the Find/Replace Dialog example there are extra panels where it doesn't seem like they're actually doing anything. In fact, they seem to mess up even more the layout (though that is probably some mistake I made somewhere) For example, the tutorial has this code:

panel = wx.Panel(self, -1)

panel1 = wx.Panel(panel, -1)
grid1 = wx.GridSizer(2, 2)
grid1.Add(wx.StaticText(panel1, -1, 'Find: ', (5, 5)), 0,  wx.ALIGN_CENTER_VERTICAL)
grid1.Add(wx.ComboBox(panel1, -1, size=(120, -1)))
grid1.Add(wx.StaticText(panel1, -1, 'Replace with: ', (5, 5)), 0, wx.ALIGN_CENTER_VERTICAL)
grid1.Add(wx.ComboBox(panel1, -1, size=(120, -1)))

panel1.SetSizer(grid1)
vbox.Add(panel1, 0, wx.BOTTOM | wx.TOP, 9)

Why is that different from:

panel = wx.Panel(self, -1)

grid1 = wx.GridSizer(2, 2)
grid1.Add(wx.StaticText(panel, -1, 'Find: ', (5, 5)), 0,  wx.ALIGN_CENTER_VERTICAL)
grid1.Add(wx.ComboBox(panel, -1, size=(120, -1)))
grid1.Add(wx.StaticText(panel, -1, 'Replace with: ', (5, 5)), 0, wx.ALIGN_CENTER_VERTICAL)
grid1.Add(wx.ComboBox(panel, -1, size=(120, -1)))

vbox.Add(grid1, 0, wx.BOTTOM | wx.TOP, 9)

Note that I'm not creating a panel, just adding grid1 directly to vbox.

Answer 1

I'm not sure. I've re-written the example into less code, although it's a bit hard to follow. I may e-mail this suggestions to her.

import wx

class FindReplace(wx.Dialog):
    def __init__(self, parent, id, title):
        wx.Dialog.__init__(self, parent, id, title, size=(255, 365))

        vbox_top = wx.BoxSizer(wx.VERTICAL)
        vbox = wx.BoxSizer(wx.VERTICAL)

        grid1 = wx.GridSizer(2, 2)
        grid1.Add(wx.StaticText(self, -1, 'Find: ', (5, 5)), 0,  wx.ALIGN_CENTER_VERTICAL)
        grid1.Add(wx.ComboBox(self, -1, size=(120, -1)))
        grid1.Add(wx.StaticText(self, -1, 'Replace with: ', (5, 5)), 0, wx.ALIGN_CENTER_VERTICAL)
        grid1.Add(wx.ComboBox(self, -1, size=(120, -1)))


        hbox2 = wx.BoxSizer(wx.HORIZONTAL)
        sizer21 = wx.StaticBoxSizer(wx.StaticBox(self, -1, 'Direction'), orient=wx.VERTICAL)
        sizer21.Add(wx.RadioButton(self, -1, 'Forward', style=wx.RB_GROUP))
        sizer21.Add(wx.RadioButton(self, -1, 'Backward'))
        hbox2.Add(sizer21, 1, wx.RIGHT, 5)

        sizer22 = wx.StaticBoxSizer(wx.StaticBox(self, -1, 'Scope'), orient=wx.VERTICAL)
        # we must define wx.RB_GROUP style, otherwise all 4 RadioButtons would be mutually exclusive
        sizer22.Add(wx.RadioButton(self, -1, 'All', style=wx.RB_GROUP))
        sizer22.Add(wx.RadioButton(self, -1, 'Selected Lines'))
        hbox2.Add(sizer22, 1)


        sizer3 = wx.StaticBoxSizer(wx.StaticBox(self, -1, 'Options'), orient=wx.VERTICAL)
        vbox3 = wx.BoxSizer(wx.VERTICAL)
        grid = wx.GridSizer(3, 2, 0, 5)
        grid.Add(wx.CheckBox(self, -1, 'Case Sensitive'))
        grid.Add(wx.CheckBox(self, -1, 'Wrap Search'))
        grid.Add(wx.CheckBox(self, -1, 'Whole Word'))
        grid.Add(wx.CheckBox(self, -1, 'Incremental'))
        vbox3.Add(grid)
        vbox3.Add(wx.CheckBox(self, -1, 'Regular expressions'))
        sizer3.Add(vbox3, 0, wx.TOP, 4)


        sizer4 = wx.GridSizer(2, 2, 2, 2)
        sizer4.Add(wx.Button(self, -1, 'Find', size=(120, -1)))
        sizer4.Add(wx.Button(self, -1, 'Replace/Find', size=(120, -1)))
        sizer4.Add(wx.Button(self, -1, 'Replace', size=(120, -1)))
        sizer4.Add(wx.Button(self, -1, 'Replace All', size=(120, -1)))

        sizer5 = wx.BoxSizer(wx.HORIZONTAL)
        sizer5.Add((191, -1), 1, wx.EXPAND | wx.ALIGN_RIGHT)
        sizer5.Add(wx.Button(self, -1, 'Close', size=(50, -1)))


        vbox.Add(grid1, 0, wx.BOTTOM | wx.TOP, 9)        
        vbox.Add(hbox2, 0, wx.BOTTOM, 9)        
        vbox.Add(sizer3, 0, wx.BOTTOM, 15)        
        vbox.Add(sizer4, 0, wx.BOTTOM, 9)        
        vbox.Add(sizer5, 1, wx.BOTTOM, 9)
        vbox_top.Add(vbox, 1, wx.LEFT, 5)

        self.SetSizer(vbox_top)
        self.Centre()


app = wx.App(False)
d = FindReplace(None, -1, 'Find/Replace')
d.ShowModal()
d.Destroy()
app.MainLoop()