Bug 136256 Enhance the message builder
Please see the spec attached in 133995 for detail.
UI/org.eclipse.birt.report.designer.ui.lib.explorer/src/org/eclipse/birt/report/designer/ui/lib/explorer/LibraryExplorerContextMenuProvider.java
import org.eclipse.jface.action.Separator;
import org.eclipse.jface.viewers.ISelectionProvider;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.ui.IWorkbenchActionConstants;
/**
 * This class provides the context menu for the single selection and multiple
 * selection
 * 
 * 
 */
public class LibraryExplorerContextMenuProvider extends ContextMenuProvider
{
	/**
	 * constructor
	 * 
	 * @param viewer
	 *            the viewer
	 * @param registry
	 *            the registry
	 */
	public LibraryExplorerContextMenuProvider( ISelectionProvider viewer )
	{
		super( viewer );
	}
	/**
	 * Builds the context menu. Single selection menu and multiple selection
	 * menu are created while selecting just single element or multiple elements
	 * 
	 *