Bug 32664 Package Explorer: hierarchical layout and back-linking don't work allways together.
The following triggers it: - initially 'flat layout' is used, 'link with editor' is on or off - open a java file - use 'collapse all' in the package explorer - select 'hierarchical layout' - switch 'link with editor' on or off&on -> no back-linking
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerContentProvider.java
return true;
			} else
				postAdd(parent, resource);
		}
		
		if ((flags & IResourceDelta.OPEN) != 0) {
			postProjectStateChanged(internalGetParent(parent));
			return true;		
		}
		processResourceDeltas(delta.getAffectedChildren(), resource);
		return false;
	}
	
	void setIsFlatLayout(boolean state) {
		fIsFlatLayout= state;
	}
	/**
	 * Process resource deltas.
	 *
	 * @return true if the parent got refreshed
	 */
	private boolean processResourceDeltas(IResourceDelta[] deltas, Object parent) {
		if (deltas == null)
			return false;
		
		if (deltas.length > 1) {
			
			postRefresh(parent);
			return true;
		}