Bug 6579 Packages view: can't open MANIFEST.MF of JAR file
1. Drill into a JAR with a manifest file (MANIFEST.MF) in the Packages view. Note: The JAR must be on the build path. 2. Double-click MANIFEST.MF -> nothing happens 3. From the context menu select "Open" -> nothing happens I used ant.jar in org.eclipse.ant.core as my test case.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/EditorUtility.java
ICompilationUnit workingCopy= getWorkingCopy(cu);
			if (workingCopy != null) {
				return JavaModelUtil.findMemberInCompilationUnit(workingCopy, member);
			}
		}
		return null;
	}
	
	/**
	 * Returns the compilation unit for the given java element.
	 * @param element the java element whose compilation unit is searched for
	 * @return the compilation unit of the given java element
	 */
	private static ICompilationUnit getCompilationUnit(IJavaElement element) {
		
		if (element == null)
			return null;
			
		if (element instanceof IMember)
			return ((IMember) element).getCompilationUnit();
		
		int type= element.getElementType();
		if (IJavaElement.COMPILATION_UNIT == type)
			return (ICompilationUnit) element;
		if (IJavaElement.CLASS_FILE == type)
			return null;
			
		return getCompilationUnit(element.getParent());
	}