OK--that makes sense...
because let's say I'm in FlashDevelop, and I use the equivalent "go to source" command on a native object, the file that comes up looks more like an interface definition than a true class (which is useful just the same, it's a quick way to scan for methods).
So I checked, and F3 does work for variables and custom classes...but I guess there are no dummy "source" files yet for native classes in Flex Builder 2? I can live with that...I can just go to Help, though that's slow.
So does that mean everyone has this "bug"? I just want to be sure; when you hit F3 over "MovieClip", the same error message comes up?