4289940 records a problem with exceptions thrown during disposal, e.g.

Exception during disposal:
                  java.lang.reflect.InvocationTargetException: java.lang.IllegalStateException:
                  Can't dispose InputContext while it's active

We should modify the docs for Component.removeNotify to say that client code
overriding this method should have a call to super.removeNotify as the first
line of the overriding method (as described in the evaluation for 4289940).