Bug 91409 Project Open/Close items are disabled when Package Explorer active
Project Open/Close option in the Project menu is disabled in Plugin prespective.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/workingsets/WorkingSetActionGroup.java
ISelectionProvider selectionProvider= fSite.getSelectionProvider();
		
		if (fRemoveAction != null)
			selectionProvider.removeSelectionChangedListener(fRemoveAction);
		if (fEditAction != null)
			selectionProvider.removeSelectionChangedListener(fEditAction);
		if (fCloseAction != null) {
			selectionProvider.removeSelectionChangedListener(fCloseAction);
			fCloseAction.dispose();
		}
		if (fOpenAction != null) {
			selectionProvider.removeSelectionChangedListener(fOpenAction);
			fOpenAction.dispose();
		}
	}
	
	public void fillContextMenu(IMenuManager menu) {
		super.fillContextMenu(menu);
		menu.appendToGroup(IContextMenuConstants.GROUP_REORGANIZE, new Separator(GROUP_WORKINGSETS));
		if (fRemoveAction != null && fRemoveAction.isEnabled())
			menu.appendToGroup(GROUP_WORKINGSETS, fRemoveAction);
		if (fCloseAction != null && fCloseAction.isEnabled())
			menu.appendToGroup(IContextMenuConstants.GROUP_BUILD, fCloseAction);
		if (fOpenAction != null && fOpenAction.isEnabled())
			menu.appendToGroup(IContextMenuConstants.GROUP_BUILD, fOpenAction);
		if (fEditAction != null && fEditAction.isEnabled())
			menu.appendToGroup(IContextMenuConstants.GROUP_PROPERTIES, fEditAction);
	}
}