All Dialog constructors include an "owner" input parameter. If this parameter
is null, an IllegalArgumentException is thrown. This behavior should be
specified in the javadoc. Also, the Window constructor Window( Window owner)
needs to specify that IllegalArgumentException is thrown for a null owner.

Two Dialog constructors include a "title" string parameter which may be null.
By convention, the default unspecified behavior for a null input parameter
is to throw a NullPointerException. However, the Dialog constructor accepts
null input parameters without throwing and exception. This behavior must be
specified.

It is suggested that the specification for method getTitle() also be expanded
to indicate that null may be returned for an "empty" title.

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added 4/16/98 by stevef@eng
Also need to specify that Window(Frame owner) constructer throws
IllegalArgumentException when owner is null. (Thanks for catching this Alan!)