Here is a bug that's been biting me for a couple weeks.
Here's a screenshot of Flex when it errors.
The program croaks when measureContentArea (in package
mx.containers.utilityClasses, file CanvasLayout.as ) loops through
the target's children from 0 to target.numChildren. When the
program errors: n == 112, i == 111, and target.numChildren is now
111, when it was 112 before the loop. target.numChildren has
changed while the loop is running. It's as if a child was removed
by some side effect of calls in the loop.
This baffles me because I don't see how I can debug it. I do
add and remove and insert children in my game code, but unless
ActionScript is threaded I don't see how my code can reach into a
loop in CanvasLayout.as .