Forcing a screen update?

I’m working in Air on a processor intensive function that is activated by a single button click. I have a text output box under the button that tells the user what the status of the function is. All I want to do is have the text box say “Processing…” as soon as the user presses the button, but apparently Flash insists on going straight into the more complex function first, and ends up not updating the text box for a good 30 seconds or so. Is there any way to force Flash to update the text box graphic (or the whole scene) before doing anything else?

Stephen