# Add loading progress bar and abort button
        self.progressBar = QProgressBar(visible=False)
        self.progressBar.setFormat("Loading backplot: %p%")
        self.abortButton = QPushButton('Abort', visible=False)

        hBox = QHBoxLayout()
        hBox.addWidget(self.progressBar)
        hBox.addWidget(self.abortButton)

        vBox = QVBoxLayout(self)
        vBox.addStretch()
        vBox.addLayout(hBox)

        self.abortButton.clicked.connect(self.abort)