Many modern mice and keyboard have more or less useful fancy extra buttons, like forward and backwards buttons used when browsing the Internet. Unfortunately, the hardware manufacturers haven't agreed on a standard for handling these mice, which makes it hard for application programmers to add support for such buttons.

= On Windows =
== Logitech devices ==
These drivers emit key combinations; '''alt+numpad right''' for forward, '''alt+numpad left''' for backwards. To handle this, you just need a handler for wx.EVT_CHAR:
{{{#!python 
    def OnChar(self, event):
        if event.AltDown() and event.GetKeyCode() == wx.WXK_NUMPAD_RIGHT:
            cp = self.GetDocument().GetCommandProcessor().Redo()
        if event.AltDown() and event.GetKeyCode() == wx.WXK_NUMPAD_LEFT:
            cp = self.GetDocument().GetCommandProcessor()
            if cp.CanUndo():
                cp.Undo()
}}}

== Microsoft devices ==
Microsoft has documented their behaviour very well. See for example [[http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dnwui/html/BestPracticesforSupportingMicrosoftMouseandKeyboardDevices.asp|this article]] from MSDN. They defined a few new windows messages for this.
To handle these messages I think you need to hook into the raw windows message flow (see HookingTheWndProc). I'm not an expert on wxPython, so I don't know if there's a better way of doing it. The message you need to detect is the [[http://msdn.microsoft.com/library/default.asp?url=/library/en-us/winui/winui/windowsuserinterface/userinput/keyboardinput/keyboardinputreference/keyboardinputmessages/wm_appcommand.asp|WM_APPCOMMAND]], which has the numerical ID 0x0319.

I have no idea how to implement similar behaviour on linux, but feel free to add that. Or if you have a better way of handling the WM_APPCOMMAND.