Optimise the computation of the percentage, move it closer to the data (i.e. prefs)
Enable the buttons of the letters the user is worst at (below 90% recognition) in the worst trainer panel.
Use the latest snapshot of CommonGui, as it gives a more useful stack trace when Quaqua doesn't initialise. Also, move the dependency on the Quaqua jar into the assembly/packaging module, as then it'll be on the classpath when IDEA launches.
Wire the SessionRecorder into the SessionController (so it can be used to update the view)
Update the entered text in the SessionView, and implement the SessionController's observers as inner classes rather than trying to extend two traits (which didn't work, for some reason).