Adds a new filename to the top of the list.  If the filename is \
        already loaded, it will be moved to the front of the list.
        
        :param          filename | <str>

def addFilename( self, filename ):
        """
        Adds a new filename to the top of the list.  If the filename is \
        already loaded, it will be moved to the front of the list.
        
        :param          filename | <str>
        """
        filename = os.path.normpath(nativestring(filename))
        
        if filename in self._filenames:
            self._filenames.remove(filename)
        
        self._filenames.insert(0, filename)
        self._filenames = self._filenames[:self.maximumLength()]
        
        self.refresh()