Not sure if this is a bug in the Developer Console...?
I am building some simple test classes that reference static methods in a managed package. Everything works great when I build and update the code via the standard Apex Class UI. But if I open the same, working test class in the Dev Console, make any update and try to save it, I get an error saying the class in the managed package is not visible, and it won't let me save it.
Package Visibility: Type is not visible xxx
But I can go back to the UI, update and save it there, and the tests runs without issue.
What am I missing?