So, I just upgraded to Flash CS5 and I have to say that it sucks slightly less than CS4. The IDE layout changes are for the better (unlike CS4) and it *seems* faster. But, I ran into a weird bug with one of the new features in Flash CS5: The new TLF textfield causes problems with externally loaded SWFs.

Here’s the scenario: I have a main SWF that loads another SWF at runtime. I’m using some code that I cut-and-pasted from another project to load the SWF, so I know it works. But, in my new CS5 project, it throws runtime errors whenever I try to access a public function of the loaded SWF. It can’t access any of the public methods and it keeps telling me they don’t exist. I try loading a different SWF and no problems. Huh?

In my debugging, I also noticed that when I traced the numChildren of my loaded SWF, it was wrong. It said I had 2 children when I could see that there were 4. I added another one to the timeline. It still said there were 2 children. Even weirder is that when I traced these 2 children, Flash told me that one of them was a Loader (it wasn’t). Again, I tried the same test on another SWF and it was ok.

The problem turned out to be 2 textfields that were in my loaded SWF. Flash CS5 set them as TLF Text when I created them. This is apparently the new default. The TLF text fields were breaking my loaded SWF. If I removed them, everything went back to normal. I changed the textfields from TLF Text to Classic Text and everything worked. I probably spent over an hour tracking this down.

Once I figured out what was causing the issue, I did some Googling and found this:
Flash CS5 TLF Engine Causes Errors With Loaded SWFs.

Anyway, this is a long winded way of saying be careful about using the TLF Text in Flash CS5. Oh, and…
Adobe, you suck.