Get the max size (width and height) for the elements of a list of
        strings as a QLabel.

def get_item_size(self, content):
        """
        Get the max size (width and height) for the elements of a list of
        strings as a QLabel.
        """
        strings = []
        if content:
            for rich_text in content:
                label = QLabel(rich_text)
                label.setTextFormat(Qt.PlainText)
                strings.append(label.text())
                fm = label.fontMetrics()

            return (max([fm.width(s) * 1.3 for s in strings]), fm.height())