Suppose an inner class I is declared public in its outer class O. Why might unusual syntax be required to declare a class E that extends I but is declared as a top-level class? (The required syntax is...

Suppose an inner class I is declared public in its outer class O. Why might unusual syntax be required to declare a class E that extends I but is declared as a top-level class? (The required syntax is even more bizarre than what was seen for new, but often requires bad design to be needed.)