Please update it in rawhide and F-18 and if possible in F-17.
"Mark occurrences" seems to be broken in 2.7.0, but 2.7.1 is available where it works as expected (tested in an eclipse version downloaded from eclipse.org).
Dieter, Thank you for the note. I am updating Pydev to 2.7.1
eclipse-pydev-2.7.1-1.fc18 has been submitted as an update for Fedora 18. https://admin.fedoraproject.org/updates/eclipse-pydev-2.7.1-1.fc18
Package eclipse-pydev-2.7.1-1.fc18: * should fix your issue, * was pushed to the Fedora 18 testing repository, * should be available at your local mirror within two days. Update it with: # su -c 'yum update --enablerepo=updates-testing eclipse-pydev-2.7.1-1.fc18' as soon as you are able to. Please go to the following url: https://admin.fedoraproject.org/updates/FEDORA-2012-19057/eclipse-pydev-2.7.1-1.fc18 then log in and leave karma (feedback).
eclipse-pydev-2.7.1-1.fc18 has been pushed to the Fedora 18 stable repository. If problems still persist, please make note of it in this bug report.