That said: ohmigod, the documentation is such a mess. It's improving, and they're getting to the point where it's decent for conventional applets -- a tad scattershot and cryptic, but most of the information is there. But when you try to do something sophisticated, you're left with little choice but to dig into the source code (not exactly well-commented itself).
None of this is surprising, of course: open source projects are largely at the mercy of what the programmers want to do, and most programmers don't like writing documentation. But man -- it would all be so much more useful if there was a clear documentation plan here...