SQL & PL/SQL

Hi
I executed the following code in PL/SQL Developer :

CREATE OR REPLACE PACKAGE EMP_PACK AS
TYPE EMPCURTYP IS REF CURSOR RETURN EMP%ROWTYPE;
PROCEDURE EMP_PROC( EMP_CUR IN OUT EMPCURTYP);
END EMP_PACK;


CREATE OR REPLACE PACKAGE BODY EMP_PACK AS
PROCEDURE EMP_PROC(EMP_CUR IN OUT EMPCURTYP) IS
BEGIN
OPEN EMP_CUR FOR SELECT * FROM EMP;
END EMP_PROC;
END EMP_PACK;
/

When I executed the following command , I got the following statement

SQL> variable var refcursor;
REFCURSOR not supported

The same statement is working in SQL*Plus environment

How is it to be executed in PL/SQL Developer ?