Checked and not a bug.
This can arise when painting is not done on the EDT. In that case, paint calls to other components in the AWT/Swing hierarchy can become intermixed and maybe then collapsed by the RepaintManager. The "fix" is always to paint on the EDT.
An additional step of switching off double buffering on the RepaintManager for the duration of the paint might also be needed I guess - but seems not to be.
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Output sometimes includes garbage on Windows platforms.
This needs fixing. The code was developed on a Mac where the problem does not arise.
Checked and not a bug.
This can arise when painting is not done on the EDT. In that case, paint calls to other components in the AWT/Swing hierarchy can become intermixed and maybe then collapsed by the RepaintManager. The "fix" is always to paint on the EDT.
An additional step of switching off double buffering on the RepaintManager for the duration of the paint might also be needed I guess - but seems not to be.