We are making a system that has a main swf for the application, and loads separate tools from separate swfs -- there will be versioning issues in the future since the s
I did misunderstand what you are trying to do.
Well, actually, I guess there is no handler for verify error and to detect it, you have to fight with byte-codes.
By the way, I have and idea which is not the very answer for your question but may helps you.
a 3rd party swf is depending on a class that should be in my swf -- if that class is missing I get the VerifyError.
From this point, I can advice that if you link the 'missing class' into your swf and load the 3rd party swf into ApplicationDomain.currentDomain or new ApplicationDomain(ApplicationDomain.currentDomain), you can avoid the 'Verify Error'. (This is because the flash player will find the diffinition of the missing class in the parent swf.)
Here is my sample code which loads a swf with verify error(http://teionclub.com/test/xml/main.swf).
Avoiding VerifyError - wonderfl build flash online