Memory
I'm almost embarassed that 0.2.3 is going to be out less than a month after 0.2.2, but I guess that's the way it all falls out sometimes. Anyhow, the new buttons support internal state management (i.e., they know when they are "active" and when they're "disabled"), can have images, are sizable to any size you choose, are fully themed, and they support both inline and programatic constructors.
On another note, I wish I had a good way to determine how much memory each object and component in the NW environment requires. But I suppose that needing memory optimization for DHTML is a pretty sure sign that I'm doing something unholy. Doesn't mean that I don't want it though.