Logged In: YES 
user_id=764593

(1)  Why was the behavior different before?  Is 10 times 
per second not responsive enough?  Does a busy-wait of 
10 times per second cause too much thrashing?

(2)  It seems like the problem isn't really about Tkinter so 
much as it is about event loops vs threading.  The event 
loop is infinite, so nothing else *in that thread* will happen 
after it.  This isn't solvable with a single-threaded python.  
(On the other hand, single-threaded python should never 
have the mutex problem you mentioned.)

(3)  With multi-threaded python, is there any reason not to 
start the event loop in a fresh thread?  (And let that new 
thread block waiting for events.)  This would also reduce 
contention with other frameworks that want to treat the 
"main" thread differently.