First of all I'm not asking for legal advice but just checking if anyone agrees with my suspicions. That might help in convincing Sencha to change their license.
Their commercial license says:
The Open Source version of the Software (“GPL Version”) is licensed under the terms of the GNU General Public License versions 3.0 (“GPL”) and not under this License Agreement. If You, or another third party, has, at any time, developed all (or any portions of) the Application(s) using the GPL Version, You may not combine such development work with the Software and must license such Application(s) (or any portions derived there from) under the terms of the GNU General Public License version 3, a copy of which is located at http://www.gnu.org/copyleft/gpl.html.
Meanwhile there exist libraries licensed under MIT or BSD, that use ExtJS. GeoExt is one example. It's likely some contributors of those libraries have not bought the commercial license of Ext JS, and are using its GPL-licensed version. Reasonably GPL-licensed Ext JS shouldn't "infect" GeoExt code if it's distributed without the Ext JS library.
Now the problem is, if I use GeoExt then likely "portions" of it have been "developed using" the GPL version. Specifically Sencha clarifies what they mean by "develop using" in their FAQ:
The license prohibits combining code that you develop using a GPL licensed version of the software with code that you develop using a commercial licensed version. In other words, you may not begin development with our GPL version and then "convert" it to our commercial version.
My interpretation is that it's not allowed by the Sencha commercial license to combine Ext JS with GeoExt and who knows what other libraries whose contributors at some point may have "developed using" a GPL version of Ext JS. This may or may not include OpenLayers, jQuery and other libraries developers would likely also need to use in their commercial projects.
If Sencha then so desires, according to their commercial contract they can demand commercial customers who combined Ext JS with other libraries, to release their software under the GPL, since the commercial license doesn't offer any other resolution.
My question is: do you agree that this sounds like developing commercial software using Ext JS may be risky, or is my interpretation incorrect?
Best Answer
As far as I can determine, the commercial license forbids the development of libraries, because libraries permit a third party to do software development using Ext JS.
This means that any libraries that are built upon Ext JS must, by necessity, be using the GPL version of Ext JS.
By extension, if you use any of those libraries in your own application, you are also forbidden from using the commercial version of Ext JS.
I am not familiar enough with how the GPL interacts with JS to be able to tell in how far the use of the GPL version of Ext JS "infects" the rest of the code.