Does a GPL API infect its apps?

[Ken Arromdee]

Now that I think about it, there's an even weirder result.

Suppose I add a function to a GPL program, and I want to dual license the
function so that it can be used with the GPL program but can also be used in
way X (where X is not permitted by GPL.  For instance, "may be used as a
Netscape plugin".)

I add the function to the GPL program, and then I add a copyright statement
saying that the function in question is dual-licensed under GPL+X.

Now we get into semantics.  If dual-licensed means "is under a single license
GPL+X whose terms mean that you can use it in either of two ways", then I
cannot do this, because functions added to the GPL'ed program must be GPL'ed.
The single license GPL+X is not GPL, so it is not allowed.

If dual-licensed means "under a single license which may be one of (GPL, X),
selected by the recipient", then every time the recipient selects X, he's
received a GPL program with an added function licensed under X--this makes me
a GPL violator depending on the whim of the recipient.

The upshot of this?  If I want to send someone a GPLed program with a function
of mine, and I want the function to have additional permissions, I have to
*send them two copies of the function*.  This is bizarre.  (I can't even
relicense the copy they already have--that would retroactively create one of
the two above cases and thus retroactively make me a GPL violator.)