If you have a normal Java class in Greenfoot with source code available, you can view the Javadoc by opening the editor and using the top-right dropdown to switch to documentation view. However, if you have either a Stride class, or a Java class without source code, there is no way to get at the documentation. This is problematic for classes without source code, as a teacher might provide these but leaves the students without a way to view the source code.
In BlueJ, we offer the "Open Editor" option on classes without source, and when it opens we show the Javadoc. But in Greenfoot we don't show the open editor option if a class has no source code available.
We should allow viewing the documentation via a right-click context menu item, either on all classes, or at least on those without source. I'd prefer showing an "Open documentation" action rather than "Open editor" as being clearer. (We could swap BlueJ's menu item title to "Open documentation", too.)