gdb output:
(gdb) r
Starting program: /home/user/builds/lmms/src/lmms-0.4.5/lmms
[Thread debugging using libthread_db enabled]
[New Thread 0x7f2f0e4b2750 (LWP 5655)]
[New Thread 0x7f2efca30910 (LWP 5658)]
[New Thread 0x7f2ee72dc910 (LWP 5659)]
[New Thread 0x7f2ee69b7910 (LWP 5660)]
[New Thread 0x7f2ee61b6910 (LWP 5661)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7f2f0e4b2750 (LWP 5655)]
0x00007f2f0aeb8869 in _int_malloc () from /lib/libc.so.6
(gdb) bt
#0 0x00007f2f0aeb8869 in _int_malloc () from /lib/libc.so.6
#1 0x00007f2f0aeba7de in malloc () from /lib/libc.so.6
#2 0x00007f2f0d1365ed in QListData::detach2 () from /usr/lib/libQtCore.so.4
#3 0x00007f2f0d20f44e in ?? () from /usr/lib/libQtCore.so.4
#4 0x00007f2f0d2069c3 in QObjectPrivate::refSender () from /usr/lib/libQtCore.so.4
#5 0x00007f2f0d209177 in QMetaObject::connect () from /usr/lib/libQtCore.so.4
#6 0x00007f2f0d209667 in QObject::connect () from /usr/lib/libQtCore.so.4
#7 0x000000000053a103 in automationPattern::addObject (this=0x2127100, _obj=0x2124990,
_search_dup=<value optimized out>) at /home/user/builds/lmms/src/lmms-0.4.5/src/core/automation_pattern.cpp:113
#8 0x000000000054df53 in note::createDetuning (this=0x7fff8664d550)
at /home/user/builds/lmms/src/lmms-0.4.5/include/inline_automation.h:66
#9 0x00000000005a9da1 in instrumentTrack::processInEvent (this=0x1ed83d0, _me=@0x7fff8664d650, _time=@0x7fff8664d6a0)
at /home/user/builds/lmms/src/lmms-0.4.5/src/tracks/instrument_track.cpp:239
#10 0x0000000000526991 in pianoView::mouseMoveEvent (this=0x203d0e0, _me=0x7fff8664dea0)
at /home/user/builds/lmms/src/lmms-0.4.5/src/core/piano.cpp:670
#11 0x00007f2f0d90b912 in QWidget::event () from /usr/lib/libQtGui.so.4
#12 0x00007f2f0d8bd0cc in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#13 0x00007f2f0d8c41e1 in QApplication::notify () from /usr/lib/libQtGui.so.4
#14 0x00007f2f0d1f85bc in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#15 0x00007f2f0d8c3ab0 in QApplicationPrivate::sendMouseEvent () from /usr/lib/libQtGui.so.4
#16 0x00007f2f0d9299e4 in ?? () from /usr/lib/libQtGui.so.4
#17 0x00007f2f0d9286ba in QApplication::x11ProcessEvent () from /usr/lib/libQtGui.so.4
#18 0x00007f2f0d95089c in ?? () from /usr/lib/libQtGui.so.4
#19 0x00007f2f09e81dbe in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#20 0x00007f2f09e85568 in g_main_context_iterate () from /usr/lib/libglib-2.0.so.0
#21 0x00007f2f09e85690 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#22 0x00007f2f0d220a86 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#23 0x00007f2f0d95007e in ?? () from /usr/lib/libQtGui.so.4
#24 0x00007f2f0d1f6ec2 in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#25 0x00007f2f0d1f7294 in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#26 0x00007f2f0d1f9449 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#27 0x000000000052a160 in main (argc=1, argv=<value optimized out>)
at /home/user/builds/lmms/src/lmms-0.4.5/src/core/main.cpp:490