Flex :: Air - Dialog Not Display Immediately?

In an AIR application I have the following code:

theDialog = PopUpManager.createPopUp( this, TheDialogClass, true ) as TheDialogClass;
theDialog.addEventListener(FlexEvent.CREATION_COMPLETE, cpuIntensiveCalc);

At the end of cpuIntensiveCalc the dialog is removed. The dialog informs the user that "something is going on, please stand by."

The problem is that cpuIntensiveCalc starts before the dialog draws. So the user experience is that the application freezes for 10 seconds with no indicator, then the modal dialog flashes quickly (less than a second) on screen.

The Adobe docs say this about creation_complete

Dispatched when the component has finished its construction, property processing, measuring, layout, and drawing.

So this feels like the correct event. In the name of completeness, I also tried

theDialog = PopUpManager.createPopUp( this, TheDialogClass, true ) as TheDialogClass;
cpuIntensiveCalc();