Ext JS is some sort of Javascript framework stuff. I know nothing whatsoever about Javascript, but what interested me was the slightly odd license. If you're a non-profit you can have it under the LGPL 3.0, but if you want to use it in a library then you have to buy a commercial license for them. This seems at odds with my understanding of the LGPL, but anyway. I'm a non-profit, so I've downloaded it under the LGPL. Under my LGPL rights, I've put it up for download here. If you want to use it in a library, feel free to do so as long as you abide by version 3.0 of the LGPL.

Thanks to Decklin for pointing this out.