Threds and Control Window

[Askari]

When I try to control a window (toplevel) with a thread (not the main
thread), I can't set the 'visible' of the window with this example :
      app.state("withdrawn")

In the main thread, I have no problem, but in other thread, the
application freze.

Note : I have no choice to put the "app.state("withdrawn")" in my
thread and not in the main thread. Why, because it's for pop a window
when the thread see a error and for query the user how do (the thread
must wait the answer before continue the own execution). I try with
the module "tkMessageBox" but him too do frezed the application.

Brienfly, how I can control a window (toplevel) with a thread other
that the main thread?

Askari