The news that Ext-JS has, from one release to the next, changed from a modified LGPL to a GPL based license nearly made me fall off my chair. There have been many poor judged, and ill advised decisions made by software companies over the last few years, but this has got to be up there with the stupidist I've seen and I'm not even personally an Ext-JS user.
What they have effectively done is built up a community, taking full advantage of the open source model by accepting user contributions and patches and then turned around and kicked their own community up the backside. It is projects like Ext-JS that give open source a bad name. How can a company have faith in open source if the people behind it can't even decide how to license the thing?
When you start off in the software business you have to very early on decide whether you are an open source company or whether you are a commercial software company. If you choose the former then you need to choose an appropriate license. For platforms the GPL license can make a lot of sense (think Linux and Java) to prevent forks, force contributions etc. although I'm still not a big fan of it.
On the otherhand for libraries or frameworks only a few licenses make sense (Apache 2.0, MIT, BSD and to a lesser extent LGPL). With Grails we went for Apache 2.0 as one of the most liberal licenses out there. Once you've decided on the license as an open source company your job is the grow the community by attracting users who put faith in your product and the fact that its licensed in a liberal way. Those users would not come in the first place if you had a restrictive license.
By choosing the open source route you have made a decision as a company to promote the community driven approach. Of course this doesn't stop you from releasing a commercial version, you could dual license it as Ext-JS have done for those who want the comfortable feeling of paying for something. You cannot however, have it both ways you are either an open source company or you are not. Ext-JS seem to be stuck in 2 minds as to whether they really are an open source company, it is this indecisiveness that is going to see their community go elsewhere.
It is not like they're unique either, the Ajax framework space is super competitive and they've just dropped the ball and given their competitors a big advantage. My personally prediction on this one is that they'll lose a lot of users, probably to Yahoo UI and jQuery UI or possibly Dojo. Something else will soon come along to fill their space and soon they will have lost their competitive advantage, their users and all those license renewals.