Determining the source-control status of a file can be an expensive operation. CrossWorks will do this when:

A file will be in one of the following states:

If the file has been modified, its status is displayed in red in the Project Explorer. Note that if a file is not under the local root, it will not have a source-control status.

You can reset any stored source-control file status by choosing Project > Source Control > Refresh Status.