If I modify 1 file then commit it (using SVN) the File Status in the tab remains blue (modified).
Using version 8.0 build #9013. Version 8.0M1 didn't had this problem. This is an annoying bug :(
Work around is after commiting the file, modify it then revert it.
There is a JIRA ticket for this one (http://www.jetbrains.net/jira/browse/IDEA-18893) which was created on July 27, 2008 but Version 8.0M1 was built after July 8 and didn't had this problem.