I decided to try compiling Back In Time from source after figuring out the dependencies, and it seems to start up fine. However, even with no cron-related options enabled, it tries to use crontab and fails. Installing dcron doesn't seem to resolve this.

Unless I've missed the feature, in which case I apologize, Gnome Calculator does not keep its history after closing, which Qalculate does. This is an important feature to me.