#13 Implementor actions don't get added to class file editors

[Michael R Head]

As far as I can tell, the implementors actions aren't
available when editing a .class file (with source
attached). I was browsing through some of the eclipse
classes (specifically org.eclipse.team.internal.ccvs of
org.eclipse.team.core, which I had imported as an
external plugin, but not extracted source) and found
that "open implementors" wasn't available, so I
switched to one of my other projects and opened a java
source editor and found that implementors was available.