Bug 81426 Package Explorer shows nothing after drill into working set, then show projects
I200412160800 - switch Package Explorer to working sets - context menu > Go Into a working set - Show > Projects -> view is empty -> view toolbar button 'Up to Working Sets' does not do anything
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
return fRootMode;
	}
	
	 boolean showProjects() {
		return fRootMode == ViewActionGroup.SHOW_PROJECTS;
	}
	
	 boolean showWorkingSets() {
		return fRootMode == ViewActionGroup.SHOW_WORKING_SETS;
	}
	
	private void setSorter() {
		if (showWorkingSets()) {
			fViewer.setSorter(new WorkingSetAwareJavaElementSorter());
		} else {
			fViewer.setSorter(new JavaElementSorter());
		}
	}
	
	
	
	public void internalTestShowWorkingSets(IWorkingSet[] workingSets) {
		if (fWorkingSetModel == null)
			createWorkingSetModel();
		fWorkingSetModel.setActiveWorkingSets(workingSets);
		fWorkingSetModel.configured();
		rootModeChanged(ViewActionGroup.SHOW_WORKING_SETS);
	}
}