The AP Tuner 3 version is being developed to provide a more detailed view of the note being played. In addition, we are working on a new kind of visualization window called the "Harmonic Deviation Window". Also we are working on support for temperament and stretch options.
We have just completed the AP Tuner 3.0 Beta! If you have any suggestings for the next release, feel free to send an email to Joseph Broms at firstname.lastname@example.org
Below is a screen shot of what the Harmonic Deviation Window should look like after playing an A2 on the guitar. Notice that is the window shows the frequency of each harmonic (blue) over time. To be able to see all the harmonics is a reasonable level detail, all the harmonics are divided by thier harmonic number - thus the harmonic overlap. In a situation where the note were inharmonic, the harmonics would visually climb upwards. In red is shown the relevant harmonics of the reference note, which right now is E2. Because E2 is a third below A2, only the 4th harmonic of E2 is shown because it overlaps in frequency with the current note.