Classes get shared in IB between different Xcode projects in an Xcode 4 workspace. Why?

I have two projects in a Xcode 4 workspace.

Then, I drag a new Object into my XIB file in one of the project to instantiate a new object. Why on earth can I choose as the object's class a class in the other project? This is messed up, 开发者_JAVA百科and causes weird dependencies between different projects.

I even had one case where I had two different classes in each project, but the classes had the same name. But the XIB file in one of the projects referenced the class in the other project -- not in the project in which the XIB file was!

Is this a known Xcode 4 bug, or have I got something wrong? If it's a bug, what are some potential temporary remedies to this?

RTFM. Workspaces are made so it's easy to share objects between projects in the same workspace.

Remedy: File > New > New Workspace...

Place projects in different workspaces if you want to separate them more strictly.