I've updated the FlexJS wiki with a new page about contributing to the FlexJS framework. You can find it here:
https://cwiki.apache.org/confluence/display/FLEX/Contributing+to+the+FlexJS+Framework This is a first pass so if you've been thinking about contributing, please read it through and let us know if anything could be made clearer. I used an example of creating a component as a way to walk through the process. I touched upon developing the component first in your own project, then moving it into the framework directory (and which other files need to be modified). I also mention that composite components (those made up of existing components) are good candidates for 100% cross-compilation into JavaScript so you don't have to create that side. Thanks, Peter Ent Adobe Systems