Tkinter / Threads: "Invalid command name"

I know, questions about Tkinter and threads have been answered very
often, but I want to ask anyway.
I am using Python 2.2 on a Linux (SuSE Linux 8.1) system.
I want to write a server application; like telnet is a client. The user
should be able to bind() to a port and wait for a client. The written
and recieved data is stored in a Text widget, self.__text. The
accept()ing is done in a seperate thread (using the threading module),
in method self.__tryConne ct().
But the seperate thread raises an exception at
self.__text["state"]="normal" .
A part of the code:

def go(self, portn):
# Open the window and connect.

# Bind self.__server to ("", portn), call listen(), ...

# When everything's ok, start the accept()ing thread.
thr=threading.T hread(target=se lf.__tryConnect )
thr.start()

def __tryConnect(se lf):
# Accept a connection
success=1
self.__text["state"]="normal" # Here the exception is raised
self.__text.ins ert("end", "Waiting for connection... ")
try: self.__client, addr=self.__ser ver.accept()
except: success=0
if not success:
self.__text.ins ert("end", "failed.\n" )
else:
self.__text.ins ert("end", "ok, connected with %s.\n" % addr[0])
self.__text["state"]="disabled"

But when I join() the thread, everything works as it should. Eventually
the self.__text reference is lost when __tryConnect() returns?
The exception is:

Exception in thread Thread-1:
Traceback (most recent call last):
...
File "...", line xx, in configure:
self.tk.call((s elf.w, configure)
TclError: invalid command name ".123123123.123 41234" ,

while ".123123123.123 41234" is the text widgets identification.
Can anyone help me?

Michael Schutte <m.*******@aon. at>