Tk not displaying correctly

[Tuvas]

I am building a TK interface, that has several threads. If all threads
are running actively, including the main one, the interface doesn't
update. For example, I have something like this, although more complex

import time, threading

master=Tk()

def thread:
  global x
  x=0
  while(TRUE):
    x=x+1
    Label(master,text=x).grid(row=0,column=0)
    time.sleep(1)

but=Button(master,command=command,text="hit me")
but.grid(row=0,column=0)

def command:
  while(x<100):
    time.sleep(1)
  x=0

t=threading.Thread(target=thread)
t.setDaemon(1)
t.start()

master.mainloop()

What (I think) will happen is when you hit the button, until x=100, the
display will stop updating, and when the command has left it's thread,
it will return to updating again. Is there a way to make it so it
always will update, irreguardless if it's in a seporate thread, perhaps
calling a new thread that calls mainloop? Thanks!