How can I update a wxStaticBitamp?

Question

[PROBLEM]
I want to update the wxStaticBitamp image if the user clicks on some item from wx.TreeCtrl.

[CODE]

import wx
app = wx.App(redirect=False)
top = wx.Frame(None)
sizer = wx.GridBagSizer()

def createHelpWindow(event):
    import wx  
    locale = wx.Locale(wx.LANGUAGE_ENGLISH)
    frame = wx.Frame(None, wx.ID_ANY, " Help contents", style=wx.MINIMIZE_BOX | wx.CAPTION | wx.CLOSE_BOX) # A Frame is a top-level window.
    frame.Center()
    frame.SetBackgroundColour('LIGHTGREY')
    frame.SetSize(800,600)
    sizer = wx.GridBagSizer()

    # Add control tree
    treeHelp = wx.TreeCtrl(frame, wx.ID_ANY, wx.DefaultPosition, wx.DefaultSize, wx.TR_DEFAULT_STYLE )
    sizer.Add(treeHelp,(1,1),(19,23),wx.EXPAND)

    # Add description box
    helpDisplay = wx.StaticText( frame, wx.ID_ANY, "", wx.DefaultPosition, wx.DefaultSize, 0, )
    sizer.Add(helpDisplay,(1,26),(1,1),wx.EXPAND)

    # Create image object
    chooseMessageImage = wx.StaticBitmap( frame, wx.ID_ANY, wx.Bitmap(wx.NullBitmap), wx.Point( 300,110 ),wx.DefaultSize, 0)
    def OnSelChanged(event):
        locale = wx.Locale(wx.LANGUAGE_ENGLISH)
        chooseMessageImage = wx.StaticBitmap( frame, wx.ID_ANY, wx.Bitmap(wx.NullBitmap), wx.Point( 300,110 ),wx.DefaultSize, 0)
        item =  event.GetItem()

        # Display the selected item text in the text widget
        print "selected ", treeHelp.GetItemText(item)
        if treeHelp.GetItemText(item) == 'TFT':
            helpSecondDisplay.SetLabel("""test page for landing page""")
            chooseMessageImage.SetBitmap(wx.NullBitmap) # Set image object to null
        #################### End main #########################
        elif treeHelp.GetItemText(item) == 'Main page':
            helpSecondDisplay.SetLabel("""test txt for main page""")
            chooseMessageImage.SetBitmap(wx.Bitmap( u"create_images/add_message.png", wx.BITMAP_TYPE_ANY)) # Set image to some src  
    treeHelp.Bind(wx.EVT_TREE_SEL_CHANGED, OnSelChanged)
    helpSecondDisplay = wx.StaticText( frame, wx.ID_ANY, "Lorem ipsum", wx.DefaultPosition, wx.DefaultSize, 0, )
    sizer.Add(helpSecondDisplay,(3,26),(1,1),wx.EXPAND)   
    root = treeHelp.AddRoot('TFT')
    rootMainPage = treeHelp.AppendItem(root, 'Main page') 
    treeHelp.Expand(root)

    # Wrap it up
    frame.SetSizer(sizer)
    frame.Center()    
    frame.Show(True)     # Show the frame.


# Bind the method
helpButton = wx.Button(top, wx.ID_ANY, u"help",  style=wx.BU_EXACTFIT )
sizer.Add(helpButton,(0,0),(1,1))
top.Bind(wx.EVT_BUTTON, createHelpWindow, helpButton)  
top.Sizer = sizer
top.Sizer.Fit(top)
top.Show()
app.MainLoop()

[CURRENT]
The image object (chooseMessageImage) is shown when I click on root.

[DESIRED]
The image object (chooseMessageImage) should not shown when I click on root.

note: when the window is loaded, the focus will be set on root but the image will not be displayed.

EDIT 1:

import wx
app = wx.App(redirect=False)
top = wx.Frame(None)
sizer = wx.GridBagSizer()

def createHelpWindow(event):
    import wx  
    locale = wx.Locale(wx.LANGUAGE_ENGLISH)
    frame = wx.Frame(None, wx.ID_ANY, " Help contents", style=wx.MINIMIZE_BOX | wx.CAPTION | wx.CLOSE_BOX) # A Frame is a top-level window.
    frame.Center()
    frame.SetBackgroundColour('LIGHTGREY')
    frame.SetSize(800,600)
    sizer = wx.GridBagSizer()

    # Add control tree
    treeHelp = wx.TreeCtrl(frame, wx.ID_ANY, wx.DefaultPosition, wx.DefaultSize, wx.TR_DEFAULT_STYLE )
    sizer.Add(treeHelp,(1,1),(19,23),wx.EXPAND)

    # Add description box
    helpDisplay = wx.StaticText( frame, wx.ID_ANY, "", wx.DefaultPosition, wx.DefaultSize, 0, )
    sizer.Add(helpDisplay,(1,26),(1,1),wx.EXPAND)

    # Create image object
    chooseMessageImage = wx.StaticBitmap( frame, wx.ID_ANY, wx.NullBitmap, wx.Point( 300,110 ),wx.DefaultSize, 0)
    def OnSelChanged(event):
        locale = wx.Locale(wx.LANGUAGE_ENGLISH)
        chooseMessageImage = wx.StaticBitmap( frame, wx.ID_ANY, wx.NullBitmap, wx.Point( 300,110 ),wx.DefaultSize, 0)
        item =  event.GetItem()

        # Display the selected item text in the text widget
        print "selected ", treeHelp.GetItemText(item)
        if treeHelp.GetItemText(item) == 'TFT':
            helpSecondDisplay.SetLabel("""test page for landing page""")
            chooseMessageImage.SetBitmap(wx.NullBitmap) # Set image object to null
        #################### End main #########################
        elif treeHelp.GetItemText(item) == 'Main page':
            helpSecondDisplay.SetLabel("""test txt for main page""")
            chooseMessageImage.SetBitmap(wx.Bitmap( "create_images/add_message.png", wx.BITMAP_TYPE_ANY)) # Set image to some src
        chooseMessageImage.Refresh()
    treeHelp.Bind(wx.EVT_TREE_SEL_CHANGED, OnSelChanged)
    helpSecondDisplay = wx.StaticText( frame, wx.ID_ANY, "Lorem ipsum", wx.DefaultPosition, wx.DefaultSize, 0, )
    sizer.Add(helpSecondDisplay,(3,26),(1,1),wx.EXPAND)   
    root = treeHelp.AddRoot('TFT')
    rootMainPage = treeHelp.AppendItem(root, 'Main page') 
    treeHelp.Expand(root)

    # Wrap it up
    frame.SetSizer(sizer)
    frame.Center()    
    frame.Show(True)     # Show the frame.


# Bind the method
helpButton = wx.Button(top, wx.ID_ANY, u"help",  style=wx.BU_EXACTFIT )
sizer.Add(helpButton,(0,0),(1,1))
top.Bind(wx.EVT_BUTTON, createHelpWindow, helpButton)  
top.Sizer = sizer
top.Sizer.Fit(top)
top.Show()
app.MainLoop()

Answer 1

problem solved. The final working code is:

import wx


app = wx.App(redirect=False)
top = wx.Frame(None)
sizer = wx.GridBagSizer()

def createHelpWindow(event):
    import wx
    locale = wx.Locale(wx.LANGUAGE_ENGLISH)
    frame = wx.Frame(None, wx.ID_ANY, " Help contents", style=wx.MINIMIZE_BOX | wx.CAPTION | wx.CLOSE_BOX) # A Frame is a top-level window.
    frame.Center()
    frame.SetBackgroundColour('LIGHTGREY')
    frame.SetSize(800,600)
    sizer = wx.GridBagSizer()
    # Add control tree
    treeHelp = wx.TreeCtrl(frame, wx.ID_ANY, wx.DefaultPosition, wx.DefaultSize, wx.TR_DEFAULT_STYLE )
    sizer.Add(treeHelp,(1,1),(19,23),wx.EXPAND)
    # Add description box
    helpDisplay = wx.StaticText( frame, wx.ID_ANY, "", wx.DefaultPosition, wx.DefaultSize, 0, )
    sizer.Add(helpDisplay,(1,26),(1,1),wx.EXPAND)
    # Create image object
    chooseMessageImage = wx.StaticBitmap( frame, wx.ID_ANY, wx.NullBitmap, wx.Point( 300,110 ),wx.DefaultSize, 0)
    def OnSelChanged(event):
        locale = wx.Locale(wx.LANGUAGE_ENGLISH)
        item =  event.GetItem()
        # Display the selected item text in the text widget
        print "selected ", treeHelp.GetItemText(item)
        if treeHelp.GetItemText(item) == 'TFT':
            helpSecondDisplay.SetLabel("""test page for landing page""")
            chooseMessageImage.SetBitmap(wx.NullBitmap) # Set image object to null
        #################### End main #########################
        elif treeHelp.GetItemText(item) == 'Main page':
            helpSecondDisplay.SetLabel("""test txt for main page""")
            chooseMessageImage.SetBitmap(wx.Bitmap( "create_images/add_message.png", wx.BITMAP_TYPE_ANY)) # Set image to some src
            frame.Refresh()
    treeHelp.Bind(wx.EVT_TREE_SEL_CHANGED, OnSelChanged)
    helpSecondDisplay = wx.StaticText( frame, wx.ID_ANY, "Lorem ipsum", wx.DefaultPosition, wx.DefaultSize, 0, )
    sizer.Add(helpSecondDisplay,(3,26),(1,1),wx.EXPAND)
    root = treeHelp.AddRoot('TFT')
    rootMainPage = treeHelp.AppendItem(root, 'Main page')
    treeHelp.Expand(root)
    # Wrap it up
    frame.SetSizer(sizer)
    frame.Center()
    frame.Show(True)     # Show the frame.


# Bind the method
helpButton = wx.Button(top, wx.ID_ANY, u"help",  style=wx.BU_EXACTFIT )
sizer.Add(helpButton,(0,0),(1,1))
top.Bind(wx.EVT_BUTTON, createHelpWindow, helpButton)
top.Sizer = sizer
top.Sizer.Fit(top)
top.Show()
app.MainLoop()

My mistake was that I created the bitmapObj inside OnSelChanged method.