Before you spend any significant amount of time trying to figure out what APIs are available for enabling drag and drop on the Spark DataGrid, I thought I’d put it out there that it will not be available in the first Hero release of the component. In flash builder, I think you will get code hints for events like dragComplete, dragStart, dragEnter, dragOver, however, you won’t find the properties dragEnabled or dropEnabled.
I believe that the team plans to add drag and drop support in the next big release after Hero, but, features haven’t been set in stone and I certainly can’t promise anything.
For now, if you really need drag and drop in a Spark DataGrid, you are left writing your own. Sorry :( I was disappointed to hear the news too.