Bug 146088 Add library context menu item not available in empty Library Explorer
Steps to reproduce: 1. Make sure there are no libraries in your resource folder. Right-click in Library Explorer. 2. If libraries exist in the resource folder, expand a library and highlight an item that is inside the library. Right-click in Library Explorer. Expected: Add Library is available in the context menu in both cases. Use Library is available in the context menu in case 2. Actual: Only Refresh is available in the context menu. It should not be necessary to select a library in order to add a library.
UI/org.eclipse.birt.report.designer.ui.lib.explorer/src/org/eclipse/birt/report/designer/ui/lib/explorer/LibraryExplorerContextMenuProvider.java
* 
	 * 
	 * @param menu
	 *            the menu
	 */
	public void buildContextMenu( IMenuManager menu )
	{
		if ( Policy.TRACING_MENU_SHOW )
		{
			System.out.println( "Menu(for Views) >> Shows for library" ); 
		}
		menu.add( new Separator( IWorkbenchActionConstants.MB_ADDITIONS ) );
		IStructuredSelection selection = (IStructuredSelection) getViewer( ).getSelection( );
		if ( selection != null && selection.getFirstElement( ) != null )
		{
			Object selected = selection.getFirstElement( );
			refreshExplorerAction.setSelectedElement( selected );
			menu.add( refreshExplorerAction );
			menu.add( new Separator( ) );
			if ( selected instanceof File )
			{
				if ( ( (File) selected ).isDirectory( ) )
				{
					addLibraryAction.setFolder( (File) selected );
					menu.add( addLibraryAction );
				}
				else
				{
					addLibraryAction.setFolder( ( (File) selected ).getParentFile( ) );
					menu.add( addLibraryAction );