Running user scripts in a Tkinter app?

[Russell E. Owen]

I have a Python/Tkinter remote control application and want to add 
support for running user scripts.

I would like the scripts to be written in python, would like them to be 
able to update Tkinter widgets and (the hard part) would also like them 
to be capable of pausing until some condition is met (e.g. a remote 
control command finishes) without hanging the event loop.

I plan to add a library of routines to send commands and wait for 
specific replies. For example:
- call(cmd) sends a command string to the remote host and returns a 
"command object" that keeps track of the state of the command
- waitcmd(cmd_obj) pauses the script (but not the overall application) 
until cmd_obj finishes or fails

I'm confused as to the best way to write the "waitcmd" function. It 
seems like a good place to use threads, but my understanding is that 
Tkinter is not thread safe.

The only solution I've thought of is to try to recreate the Tkinter main 
loop within the wait function. Very crudely:

tkobj = Tkinter.Frame()

def waitcmd(cmd_obj):
  while not cmd_obj.isdone():
   tkobj.update()

I think this will work, but am worried it will be much slower than the 
usual Tkinter main event loop. If there was some way to start a new 
Tkinter event loop (while the main loop is paused) and terminate this 
new loop when the wait was finished, that'd be perfect.

Any suggestions? Would this be easier in some other GUI library?

-- Russell