strange Tkinter problem

[tjiit]

I have an application using a Tkinter GUI which starts a network
connection if you click on a button. The strange thing is that the GUI
freezes and the connection is established. Does this mean that Tkinter
executes the functions bound do an event and then returns when the
function has ended? I thought it would to kinda multi-threading so it
could handle large events and keep interactive while doing it.
Can anyone give me a (some) hints?

    - tjiit