A little confusion about libraries configuration

IDEA supports 3 kinds of libraries: Global, Project and Module. Assume that my project has 2 modules and these modules depend on a library which I already set as a GLOBAL library. At this time, I can set it as a dependency of these modules (via Add | Global library... in Dependencies tab) twice. But I cannot set it, this GLOBAL library, to be a PROJECT library.

And I think a PROJECT library should be set to be a module's dependency automatically.

Should IDEA help me to do them?