Importing Flash Builder projects into FDT

it seems like Adobe won't continue with the development of FB, so I am thinking about using FDT instead. However I somehow struggle to get my FB projects to run in FDT. In my FB workspace I am using multiple Flex library projects a Mobile and a Desktop Flex Project that are based on the library projects. Now I have tried to import the projects into FDT - they compile, and I get them to run on the simulator but as the App starts, I get many errors like:

VerifyError: Error #1014: Class Spark.skins.mobile.supportClasses::ButtonBarButtonSkinBase could not be found.

or

Class spark.components::Application could not be found.

Here are the steps that I made to import the FB projects into FDT:

1. Import all Projects with File->Import
2. Added Flash Nature to all the projects
3. Set the project type to AIR Flex for library projects and desktop projects, AIR Mobile Flex for mobile Projects
4. Added the src folder and libs folder and all the swcs in the lib folder to the classpath.
5. Added projects that are used by other projects into the build path of those Projects
6. Building of some projects gave me a warning like: ="The swc-file-name has style defaults and is in the library-path, which means dependencies will be linked in without the styles. This can cause applications, which use the output swc, to have missing skins. The swc should be put in the external-library-path." So I checked the checkbox for each of those SWCs in the FDT Build Path to use the SWCs as Runtime Shared Code. After that the warning went away.

After that I was able to build everything without a warning or an error. However when running the app in the simulator it crashes immediately with hundreds of the errors from above. I tried to add more SWCs as Runtime Shared Code in the Mobile Project which did not solve the problem either. It seems like the Mobile Project is not able to access those basic libraries and also not my library projects.

What am I doing wrong? :-/

Verify that the spark.swc and all other required SDK swc for your Air Applications are in the Project Properties/FDT Build Path/SDK Library.

The class spark.components.Application is located inside the spark.swc