Well, this has lead to ongoing discussions in the community ("Thread from hell") and attacks by developers who sell their components under a proprietary license. In fact even some helpers and developers quit their job in the workgroups (most sadly also Marko Schmuck, who maintained openSEF, openWiki and openWordpress. Marko has now switched over to the Mambo project, thinking that this is the better choice for his business.)
Over all this topic has lead to much confusion - some people even think Joomla! is about to fork.
I don't want to comment on that, but all I can say is that VirtueMart will stick with Joomla!. Future Versions of VirtueMart will be able to run natively on Joomla! 1.5 (without the legacy support).
Going to the Mambo Project is not an option. In my opinion (correct me), Joomla! has a much brighter future and a stronger community.
VirtueMart currently offers different ways to extend its functionality: you can create
- custom pages,
- VirtueMart core modules,
- shipping modules and
- payment modules.
All of these extensions won't work without VirtueMart - and as VirtueMart doesn't run without Joomla! - without Joomla!, because they were written for VirtueMart. But are they derivative works?
In my opinion they are not!
Whenever you write a shipping module, you can decide if you want to use the functions and methods VirtueMart and Joomla! offer (database access functions, URL formatting etc.) or not (write your own wrapper).
But regardless of that - when writing a custom shipping module all you have to do is to implement the official API - which is just an interface description on how VirtueMart can access the module (not the other way round).
This means that the VirtueMart Project tolerates proprietary extensions (although they *might* be violating the GNU/GPL).
