public static function createFolder( $folderName, $mode = 0770, $userName = NULL, $groupName = NULL )
	{
		if( self::isFolder( $folderName ) )
			return FALSE;
		if( false === @mkdir( $folderName, $mode, TRUE ) )									//  create Folder recursive
			throw new RuntimeException( 'Folder "'.$folderName.'" could not be created' );
		chmod( $folderName, $mode );
		if( $userName )																		//  User is set
			chown( $folderName, $userName );												//  change Owner to User
		if( $groupName )																	//  Group is set
			chgrp( $folderName, $groupName );
		return TRUE;
	}