I decided to download FB4 and I opened a project that I had been working on in FB3 and I got these errors:
The style 'backgroundGradientAlphas' is only supported by type 'mx.core.WindowedApplication' with the theme(s) 'halo'. I found out how to fix this in FB4, but I decided it would be too much trouble to try to convert this project, so I decided to go back to FB3 to finish it. So I opened the project with my FB3 and the errors are still there.
How can I get these to go away?
You don't have to convert the project, you can still use SDK 3.
1) Project properties > Flex Compiler
2) Under Flex SDK version, choose Flex 3.5
You can also import older SDKs in Window > Preferences > Flash Builder > Installed Flex SDKs.
I'm not sure how you would see compiler errors from FB4 in FB3 unless you were somehow sharing the same workspace in both. Sharing a workspace in that way is unsupported.
Jason San Jose
Software Engineer, Flash Builder