I have 2 more things with pl/sql editor.
So, when you have authid clausule in package aspecyfication, code explorer does not lists variables and types list.
The other thing is that ctrl+space does not work for variables declared in spec. (of course when you have authid clausule).
Watch attachement, there are two almost identical packages, one of them has AUTHID DEFINER clausule. Check this things, i wrote about.