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/OpenCloseWorkingSetAction.java
protected String getErrorTitle() {
				return WorkingSetMessages.OpenCloseWorkingSetAction_close_error_title; 
			}
			protected String getErrorMessage() {
				return WorkingSetMessages.OpenCloseWorkingSetAction_close_error_message; 
			}
		};
	}
	public static OpenCloseWorkingSetAction createOpenAction(IWorkbenchSite site) {
		return new OpenCloseWorkingSetAction(site, WorkingSetMessages.OpenCloseWorkingSetAction_open_label) { 
			protected boolean validate(IProject project) {
				return !project.isOpen();
			}
 			protected void performOperation(IProject project, IProgressMonitor monitor) throws CoreException {
				project.open(monitor);
			}
			protected String getErrorTitle() {
				return WorkingSetMessages.OpenCloseWorkingSetAction_open_error_title; 
			}
			protected String getErrorMessage() {
				return WorkingSetMessages.OpenCloseWorkingSetAction_open_error_message; 
			}
		};
	}
	
	public void dispose() {
		ResourcesPlugin.getWorkspace().removeResourceChangeListener(this);
	}
	public void selectionChanged(IStructuredSelection selection) {
		List projects= getProjects(selection);