Track tr = seq.createTrack();
Track tr1 = seq.createTrack();
assertEquals(11, seq.getTracks().length);
tr.add(new MidiEvent(new MidiMessage1(new byte[] {1, 2, 3}), 10));
assertTrue(seq.deleteTrack(tr));
assertFalse(seq.deleteTrack(tr));
assertEquals(10, seq.getTracks().length);
tr1 = null;
assertFalse(seq.deleteTrack(tr1));