Release comercial application's sources as GPL but with restr iction in usage

[Chris Yoo]

> I don't think that can happen in most realistic scenarios.
>
>
> Suppose Party A writes some software and releases it in a dually licensed
manner, one open source, the other not.
>
> Party B gets the open source version, finds a bug and fixes it,
contributing it back to some community repository.
>
> Party A CANNOT then take that fix and then put it into their dually
licensed source base unless:
>
> 1. Party B expressly gives Party A permission to do so, either thru
another license or thru relinquishing ownership of the code (either to Party
A or into the public domain).
>
>  or
>
>2. The open source license Party A originally used gives them the ability
to do so.
>
>
>I'm not aware of any open source license that meets #2 above.  Thus Party B
would have to relinquish ownership.

I don't think that Party A would have to go so far as a 'relinquishment' of
ownership - a joint assignment of copyright, as is done by OpenOffice, would
suffice (in theory). However I do agree that it is unrealistic and query how
often a contributor actually downloads and signs a copyright assignment
agreement and sends it in. 

The Q Public License (http://www.opensource.org/licenses/qtpl.php) does not
assign copyright, but purports to grant a license to the original copyright
holder to license any modifications under any license of it's choice:

"3.b. When modifications to the Software are released under this license, a
non-exclusive royalty-free right is granted to the initial developer of the
Software to distribute your modification in future versions of the Software
provided such versions remain available under these terms in addition to any
other license(s) of the initial developer."

However, is this enough to proect the original copyright holder? Does the
contributor, who still holds intellectual property rights in the
modifications, have a claim against profits made through the use of their
contributions? 

There are not any open source licenses AFAIK that incorporate copyright
assignment of modifications within. I don't think that having such a clause
would contravene any of the OSD's, and that it would remove some of the
barriers of incorporating modifications into .. (and as I write I receive
David Ryan's email to the same effect!).

Regards, 
Chris.