How to get back a file that was excluded from a build configuration in Eclipse CDT?

Using Indigo and a managed build C++ project, I right-clicked on a source file and selected Resource Configurations->Exclude From Build..., and the file promptly disappears. Scrolling down shows it at the bottom of the list of source files with a new dimmed icon. Now how do I get it back? The Reset to Default... option is always dimmed out. Right-clicking on the excluded file still only shows the Exclude From Build... option. Is there an Include in Build option somewhere? I realize I can go to .cproject file and manually edit it back in but I figure there must be a way to do it from the IDE.