The undying problem: popping up a progress bar in LWM

Hi

I almost got to the conclusion that it is impossible to pop up an 
animated progress bar in LWM.

The problem.

(a) I want to do a lengthy computation C
(b) While C is running I want a progress bar or a "wait cursor" to show 
progress P.
(c) When C is done, P should be popped down or changed to a regular 
cursor.

The obstacle.

LWM Cocoa is a single threaded thingy.


The attempted solution 1

1 - start a process with C
2 - have P work in the interface process
3 - ??????  How do I make the process C signal P that it is done?


The attempted solution 2

1 - start a process with C
2 -??????  start a process with P  ??????  How can I make this work?
3 - Have the process with C terminate the process with P


Under LWW, Solution 2 works fine.

So, what magic incantation can I do to achieve a semblance of this 
thing in LWM?  I am not beneath delving in 
low-low-low-and-implementation-dependent-not-exported functionalities 
of the Cocoa interface.

Any help appreciated.

Cheers

--
Marco Antoniotti					http://bioinformatics.nyu.edu/~marcoxa
NYU Courant Bioinformatics Group		tel. +1 - 212 - 998 3488
715 Broadway 10th FL				fax. +1 - 212 - 998 3484
New York, NY, 10003, U.S.A.