wxPython: TextCtrl delayed update when using TE_RICH(2)

[citronelu at yahoo.com]

I made a small wxPython app that retrieves web data; for visual
logging I use a TextCtrl widget, and stdout is redirected to it,
something like this:

class RedirectOutput:
    def __init__(self, objectTxtCtrl):
        self.out = objectTxtCtrl

    def write(self, string):
        self.out.WriteText(string)

[...]

messages = wx.TextCtrl(panel, -1, "", size = (-1, 200), style =
wx.TE_MULTILINE | wx.TE_RICH, name = "messages")

myout = RedirectOutput(messages)
sys.stdout = myout


The web query is inside a function (def Execute), binded to a button.
To simplify the story, consider the function looks like this:

def Execute(self, evt):
    print "Start query"
    time.sleep(5)

The "Start query" message should show in the *messages* box when I
press the button. Instead, it shows only after the time.sleep(5)
delay.

If I don't use the wx.TE_RICH / wx.TE_RICH2 style on *messages*, the
text shows before the time.sleep(5)

I want to use wx.TE_RICH / wx.TE_RICH2 because of the 64k limitation
of the standard TextCtrl.

I'm using python 2.4.3 and wxpython 2.8.1.1 unicode, on WinXP SP2.
Windows extensions are also installed.