I'd also like clarification on this. I think I remember the AGPL pissing off the ExtJS community quite a bit. From the discussion though, all it meant is that the javascript code you write to extend the library has to also be AGPL'ed. But if you bundle it with an open source app, it can be MIT, and you can still use it on top of a closed source web site.

Just like if one library cross references another GPL library, it doesnt automatically make that library GPL also. No code sharing is happening, just runtime dependencies.

But please let me know if I'm way off base here...