Chord editing does not alter Tone panel

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Create chord
2. Edit it: add tones up to 6

What is the expected output? What do you see instead?
- By adding 6-th none, ADD button should become disabled. Same does with other 
Tone buttons.

Please use labels and text to provide additional information.
- none

Original issue reported on code.google.com by [email protected] on 6 Dec 2012 at 1:54