Flex transitions are damn sexy beasts. They let you animate things like movements and resizing. The trouble is that they do all of this asynchronously, firing every so many milliseconds. The result is that occasionally, a Flex transition will get in the way of a change you make. This isn't a very long post, more of a warning. If for some reason you try to (for example) resize or move an object and find that it doesn't work, make sure that you don't have a transition overriding your size settings somewhere. Occasionally, these can fire at just the wrong moment so that you end up with exactly the wrong result, but without your really being able to see the transition happening. This happens especially if the transition is supposed to happen over a very short period of time.