scenario:
In your editor you have a statement like
foo()
and a method declaration like
def foo() {}
Now you move that method away, e.g. to some other class.
foo() will become of unknown type and will be underlined as potentially dynamic reference.
Since such an action is typically unwanted and there is no compiler warning about it,
it would be very profitable to get notified about this change of quality.
see also http://www.intellij.net/forums/thread.jspa?threadID=275240