LinuxQuestions.org - Frescobaldi 2.20.0 and slackware current

I'm running Frescobaldi (an IDE for lilypond) from my home directory, and it worked through June and july. It's crashing on startup, and I'm not sure if it's due to the rebuild of python 2.7 on September 8 or the upgrade of PyQT-4 on August 21.

other dependencies:

python-poppler-qt4 (https://slackbuilds.org/repository/1...n-poppler-qt4/), python-ly (https://slackbuilds.org/repository/1...thon/python-ly) Both of which I rebuilt last night.

The error I'm getting on startup:

Code:

Traceback (most recent call last):

  File "./frescobaldi", line 10, in <module>

    app.instantiate()              # Construct QApplication object

  File "/home/hildegard/bin/frescobaldi-2.20.0/frescobaldi_app/app.py", line 123, in instantiate

    appInstantiated()

  File "/home/hildegard/bin/frescobaldi-2.20.0/frescobaldi_app/signals.py", line 191, in emit

    l.call(args, kwargs)

  File "/home/hildegard/bin/frescobaldi-2.20.0/frescobaldi_app/signals.py", line 317, in call

    return self.func(*args[self.argslice], **kwargs)

  File "/home/hildegard/bin/frescobaldi-2.20.0/frescobaldi_app/guistyle.py", line 55, in initialize

    setStyle()

  File "/home/hildegard/bin/frescobaldi-2.20.0/frescobaldi_app/guistyle.py", line 42, in setStyle

    style = QSettings().value("guistyle", "", type("")).lower()

AttributeError: 'QString' object has no attribute 'lower

Any ideas? I don't know enough about python to know what's breaking. I'm not adverse to Frescobaldi 3, although it needs PyQT-5, python-poppler-qt5.

ETA: installed frescobaldi via it's slackbuild for the purposes of testing (repackaging the version I was using), and same error message.