I've never worked on the source and built. I see a prescription here:
Is there a shortcut? I'm literally missing one thing in a spark layout file that would allow me to submit my flex mobile app for approval and the one thing is not scheduled to be addressed in the upcoming build. Is there a fast way to simply build the spark.swc and replace in FB?
In some cases patching may help.
If the fix is simple enough you can take just the source file to be fixed, include it in your project preserving the original namespace, implement your fix and that's all.
On runtime your implementation will be loaded instead of the library's.
Hopefully that helps.
That did it. Thanks much.