def onShortcutUnindentWithBackspace(self):
        """Backspace pressed, unindent
        """
        assert self._qpart.textBeforeCursor().endswith(self.text())

        charsToRemove = len(self._qpart.textBeforeCursor()) % len(self.text())
        if charsToRemove == 0:
            charsToRemove = len(self.text())

        cursor = self._qpart.textCursor()
        cursor.setPosition(cursor.position() - charsToRemove, QTextCursor.KeepAnchor)
        cursor.removeSelectedText()
def on_lower_bound_checked_changed(self):
        if self.ui.checkBoxLowerBound.isChecked():
            self.ui.spinBoxLowerBound.setEnabled(True)
            self.ui.spinBoxBoundaryNumber.setEnabled(True)
        elif not self.ui.checkBoxUpperBound.isChecked():
            self.ui.spinBoxLowerBound.setEnabled(False)
            self.ui.spinBoxBoundaryNumber.setEnabled(False)
        else:
            self.ui.spinBoxLowerBound.setEnabled(False)