http://www.jetbrains.net/jira/browse/IDEA-18112

"Exclude from Import and Completion" has at least these use cases:

• Exclude all unwanted "sun" and "com.sun" packages which come with the JDK. Nobody should use those classes directly because they can change from one JDK version to another.
• Exclude classes from specific project libraries that are used by a different component of the project, or maybe even from some parts of my project that are not related to my code. (But because the exclude settings are system wide, this use case is not properly supported.)

The problem is that when you need to use packages such as "com.sun.sgs" (used by Project Darkstar http://www.projectdarkstar.com/), but at the same time you want to ignore all of JDK's "com.sun" packages, IDEA does not make this possible. This causes the exclude feature to be unusable. And because the exclude settings are system wide instead of being project specific, this means that you can not use them in any other project either.

Suggested solution:

Allow more complicated expressions in the exclude list. For example "com.sun -com.sun.sgs" to exclude all below com.sun except com.sun.sgs. Or make it possible to select the scope of the expressions: JDK, global library, project library, module library, project files.