Key Value Observation is over reacting

[Fred Kiefer]

While testing key value binding I found a problem with the current KVO
code. When an object is starting to get watched a new class gets cooked
up to handle the set calls on the object. Here all setter methods get
overridden, which is fine, as we don't want to change the class when
another key on the same object gets watched and this also allows to
reuse the new class for other objects.
But some of the replaced methods just don't are setters, even if the
look like. This later leads to a problem when the corresponding getter
is called and none exists. Here we should at least check, if a getter
exists and only then treat the method as a setter.

Is it OK, to change that code or is there something I overlooked?

Cheers,
Fred