Sets the Widget stylesheet.

def __set_style_sheet(self):
        """
        Sets the Widget stylesheet.
        """

        frame_width = self.style().pixelMetric(QStyle.PM_DefaultFrameWidth)
        self.setStyleSheet(QString("QLineEdit {{ padding-left: {0}px; padding-right: {1}px; }}".format(
            self.__search_active_label.sizeHint().width(
            ) if self.__search_active_label.isVisible() else 0 + frame_width,
            self.__clear_button.sizeHint().width() + frame_width)))