[ANN] animationEngine is free now

[John McKenzie]

 Tom, the original author of the software can release his or her
software in dual or multiple licences. This does not affect previous
GPL releases.

 So I could make something available under a commercial and a GPL
licence. If someone wanted it for free nothing stops them from using the
GPL version. Maybe there is something they like in the commercial
version licence though so they pay for it. Still does not stop others
from using the GPL version though.

 You are right, if it is GPL it is so forever, but the original author
can also release/re-release it with another licence. THE GPL version
with all the terms that go with it still exists though. The original
author cannot make you pick one licence or the other. Users with the GPL
continue to have all the rights of the GPL. Those users can choose to
download a copy with the other licence if they want though, as long as
they obey the terms of that licence.

 In the case of releasing the software you were discussing in the public
domain now, I can just download it again and say I have the public
domain version, not the GPL version. Or in practical terms use the GPL
one knowing that the author will not care because he wants it to be
public domain and knows I can get the public domain version easily.

 Essentially there are two versions that are identical, but have
different licences and you can choose your version based on the
licence and the GPL one will always be GPL but the author can make
other versions.