Comment 2 for bug 1611180

On the surface, this error report may appear quite bizarre, but I have spent a lot of time narrowing-down the conditions that trigger the problem.

Since Ubuntu 16.04 came out in April, I have been seeing the yellow notes, but have been unable to identify what triggered them. I finally spent a lot of time trying to narrow down the trigger, and this is what I have come up with.

A few additional points may be useful to consider:

1. You have to actually scroll the combo-box. If you just expand the combo-box, and select anything within the range displayed, the problem does not occur.

2. Even if you scroll a combo-box in another pane (such as the "F1 Help / Setup" pane's "Configuration Files" combo-box), it will affect all the other tabbed-panes.

3. Although the "Instrument" combo-box being scrolled will trigger the problem on many machines, it would not trigger the problem on all of my test machines. Only the "ASSIGNABLE" slider's combo-box (and the "Configuration Files" combo-box on the "F1" pane) will trigger the problem on all of my test machines.

4. Although the "ASSIGNABLE" slider's combo-box has both an Action-Performed and State-Change listener, the only action taken by those listeners is to log the event using System.out.println(). The configuration files combo-box, on the other hand, has a lot of side-effects.

5. It may seem far-fetched that a component in a separate panel can affect the graphics in an adjacent panel, but I can point out cases you can reproduce (bugs I have been living with for a long time without reporting) where this is definitely the case. For instance, if you hit a key to produce a note immediately to the left of one of sliders (holding it down so the dot remains displayed), and while doing so, manipulate the slider to the right of the note using the mouse, the note-dot gets erased, even though the key producing the note is left down (and the note's sound continues audibly). This problem has been observed in openjdk-7, and on Oracle Java as well. I can submit a problem report for that if you wish.

I will attached a text-file containing the System.out.println() entries in the area where the problem occurred. I did not observe anything out of the ordinary for cases with the yellow notes.