Quick bugfix release to address some issues with the audio backends: The user interface allowed selecting the PulseAudio backend, even when terminatorX was built without PulseAudio support. In addition the error message was not really helpful and PulseAudio was not set as default as it was intended.
These issues have been fixed with release 4.0.1, as usual you can find the tarball on the download page, the PPA builds are currently in progress – the resulting .deb packages should be available shortly.