Bug 114512 [working sets] Package explorer should only allow working sets that have an updater installed
I20051101-0010 The package explorer started to support working sets different than the Java working set. However, the package explorer must ensure that an working set updater is installed otherwise it will end up showing stale/bogus content.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/workingsets/WorkingSetConfigurationDialog.java
* Overrides method in Dialog
	 * 
	 * @see org.eclipse.jface.dialogs.Dialog#open()
	 */
	public int open() {
		fAddedWorkingSets= new ArrayList();
		fRemovedWorkingSets= new ArrayList();
		fEditedWorkingSets= new HashMap();
		fRemovedMRUWorkingSets= new ArrayList();
		return super.open();
	}
	/**
	 * Removes the selected working sets from the workbench.
	 */
	private void removeSelectedWorkingSets() {
		ISelection selection= fTableViewer.getSelection();
		if (selection instanceof IStructuredSelection) {
			IWorkingSetManager manager= PlatformUI.getWorkbench().getWorkingSetManager();
			Iterator iter= ((IStructuredSelection)selection).iterator();
			while (iter.hasNext()) {
				IWorkingSet workingSet= (IWorkingSet)iter.next();
				if (fAddedWorkingSets.contains(workingSet)) {
					fAddedWorkingSets.remove(workingSet);
				} else {
					IWorkingSet[] recentWorkingSets= manager.getRecentWorkingSets();
					for (int i= 0; i < recentWorkingSets.length; i++) {
						if (workingSet.equals(recentWorkingSets[i])) {
							fRemovedMRUWorkingSets.add(workingSet);
							break;
						}