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 ignoring_sigint(cls):
        """A contextmanager which disables handling sigint in the current signal handler. This
        allows threads that are not the main thread to ignore sigint.

        NB: Only use this if you can't use ExceptionSink.trapped_signals().

        Class state:
        - Toggles `self._ignore_sigint` in `cls._signal_handler`.
        """
        with cls._signal_handler._ignoring_sigint():
            yield