def eventFilter(self, widget, event):
        """
        A filter that is used to send a signal when the figure canvas is
        clicked.
        """
        if event.type() == QEvent.MouseButtonPress:
            if event.button() == Qt.LeftButton:
                self.sig_canvas_clicked.emit(self)
        return super(FigureThumbnail, self).eventFilter(widget, event)
A filter that is used to send a signal when the figure canvas is
        clicked.