Setup list widget content.

def setup(self):
        """Setup list widget content."""
        if len(self.plugins_tabs) == 0:
            self.close()
            return

        self.list.clear()
        current_path = self.current_path
        filter_text = self.filter_text

        # Get optional line or symbol to define mode and method handler
        trying_for_symbol = ('@' in self.filter_text)

        if trying_for_symbol:
            self.mode = self.SYMBOL_MODE
            self.setup_symbol_list(filter_text, current_path)
        else:
            self.mode = self.FILE_MODE
            self.setup_file_list(filter_text, current_path)

        # Set position according to size
        self.set_dialog_position()