The main incentive for the migration was to support RTL languages namely Hebrew and Japanese. Fact is that Flex 3 does not handle RTL writing properly – try writing Hebrew and English together.

After finalizing the long and fragmented process, I found that the migration had two main parts – handling the visual aspects (styling, skins etc) and handling the application logic (components and AS). I found a workaround that helped me to split the process into these two parts – i.e. set the styling to backward compatibility mode and handle the logic first. Then, once the application compiles and runs ‘properly’, disable the compatibility mode and go thru the styling issues.

So, to set the backward compatibility with Halo you should do the following: