JPanel XOR Graphics Is Wrong Color After Scrolling A Combo-Box

Normally, XOR graphics in a JPanel works fine (and is the right color).

But if you open (expand) a combo-box, and scroll it, then select the item that was formerly selected, the next time you do XOR graphics in an adjacent JPanel, the color is wrong.

In this particular case, the color being XOR'ed is pure blue (0,0,255), but instead of blue, it appears on the screen as yellow. The graphics area background is white (255,255,255).

I expected the color of the XOR'ed note-head ellipse to be blue (as it was in openjdk-7), but it was instead yellow, but it only happens after scrolling a combo-box in an adjacent panel.

This problem appeared when Open Java 8 became the default JRE in Ubuntu. It happens in most (probably all) Ubuntu variants.

aere@Aere-Dell-Inspiron:~$ lsb_release -rd
Description: Ubuntu 16.04.1 LTS
Release: 16.04

Installed version: 8u91-b14-0ubuntu4~16.04.1

I will attach the source code of part of the application that does the XOR graphics, and in that file, the following method does the XOR graphics:

public void markNote(int keyOffset)

I will also attach a Debian package which will allow you to install a 30-day free-trial version of the KeyMusician Keyboard application, which will allow you to reproduce the problem.

To reproduce the problem:

1. Run the KeyMusician Keyboard application (you can use the default, pre-loaded soundfont of the Java Sound (Gervill) synthesizer).

2. When the music-staff is displayed, type some letter keys (or click with the mouse in the musical staff graphics display area. You should see round filled dots appear, whose color is blue. This is the expected behavior.

3. Click on the combo-box above the "ASSIGNABLE" slider, which opens the combo-box. Then use its scroll-bar to scroll it all the way to the bottom, and back to the top. Then re-select what was already selected ("modulation", in the default Linux configuration).

4. Type some letter-keys (or click in the musical staff graphics area). This time, the filled-circles (the note-heads) will be yellow. They will remain yellow, even if you iconify & restore the application window, or click on other tabbed panels (for the different function keys.

The method doing the XOR graphics is the following:

    public void markNote(int keyOffset)
    {
        System.out.println("(un)markNote(" + keyOffset + ")" + "external=" + isExternalNote) ;
        if (!isSetup && keyOffset >= 0 && keyOffset < NUM_KEYS)
        {
            dim = getSize() ;
            height = dim.getHeight() ;
            width = dim.getWidth() ;
            commonSetup() ;
            double markHeight = keyWidth ;
            double markWidth = keyWidth * 1.25 ;
            double y = height - (keyOffset + 1) * keyWidth ;
            double x = shortLineStart + (shortLineLength / 2) - (markWidth / 2) ;
            System.out.println("markNote " + x + "," + y) ;
            System.out.println("BG=" + g2.getBackground() + ", FG=" + g2.getPaint() + ", newBG=" + backGround + ", newFG=" + foreGround) ; // TEMPORARY
            g2.setXORMode(backGround) ;
            g2.setColor(foreGround) ;
            if (isExternalNote)
            {
                g2.setPaint(KEY_MARK_COLOR_EXTERNAL) ;
            }
            else
            {
// g2.setPaint(KEY_MARK_COLOR) ;
                g2.setPaint(Color.BLUE) ;
            }
            Ellipse2D.Double mark = new Ellipse2D.Double(x, y, markWidth, markHeight) ;
            g2.fill(mark) ;
            System.out.println("Color=" + g2.getPaint()) ; // TEMPORARY
            g2.setPaintMode() ;
        }
    }

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: openjdk-8-jre 8u91-b14-0ubuntu4~16.04.1
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic i686
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: i386
CurrentDesktop: LXDE
Date: Mon Aug 8 19:45:42 2016
InstallationDate: Installed on 2013-05-18 (1178 days ago)
InstallationMedia: Lubuntu 13.04 "Raring Ringtail" - Release i386 (20130423.1)
SourcePackage: openjdk-8
UpgradeStatus: Upgraded to xenial on 2016-07-22 (18 days ago)