Clicking in the fret diagram editor causes crash

I am under mageia 2 64 bits.
I use musescore compiled from trunk.
I use the default score displayed in mscore at startup.
I drag and drop a fret diagram in the current score.
Then, I do a right click on the fret diagram -> fret diagram properties
Then I left click in the grey area and mscore hangs.

Here is the gdb log:

Program received signal SIGSEGV, Segmentation fault.
0x00000000008ff855 in FretCanvas::paintEvent (this=0x605a650, ev=0x7fffffff96f0) at /home/collette/repositories/MuseScore/mscore/fretproperties.cpp:155
155 if (_dots[cstring] != cfret) {
(gdb) where
#0 0x00000000008ff855 in FretCanvas::paintEvent (this=0x605a650, ev=0x7fffffff96f0) at /home/collette/repositories/MuseScore/mscore/fretproperties.cpp:155
#1 0x00007ffff39d02f6 in QWidget::event(QEvent*) () from /usr/lib64/libQtGui.so.4
#2 0x00007ffff3d8a9d6 in QFrame::event(QEvent*) () from /usr/lib64/libQtGui.so.4
#3 0x00007ffff397fcc4 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib64/libQtGui.so.4
#4 0x00007ffff3984a93 in QApplication::notify(QObject*, QEvent*) () from /usr/lib64/libQtGui.so.4
#5 0x00007ffff2c981bc in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib64/libQtCore.so.4
#6 0x00007ffff39cbf96 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib64/libQtGui.so.4
#7 0x00007ffff39ccc0f in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib64/libQtGui.so.4
#8 0x00007ffff39cbccc in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib64/libQtGui.so.4
#9 0x00007ffff3b97c08 in ?? () from /usr/lib64/libQtGui.so.4
#10 0x00007ffff39c2c60 in QWidgetPrivate::syncBackingStore() () from /usr/lib64/libQtGui.so.4
#11 0x00007ffff39d080c in QWidget::event(QEvent*) () from /usr/lib64/libQtGui.so.4
#12 0x00007ffff397fcc4 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib64/libQtGui.so.4
#13 0x00007ffff3984a93 in QApplication::notify(QObject*, QEvent*) () from /usr/lib64/libQtGui.so.4
#14 0x00007ffff2c981bc in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib64/libQtCore.so.4
#15 0x00007ffff2c9b9fa in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib64/libQtCore.so.4
#16 0x00007ffff2cc6b63 in ?? () from /usr/lib64/libQtCore.so.4
#17 0x00007fffee8a9bc3 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#18 0x00007fffee8a9f10 in ?? () from /lib64/libglib-2.0.so.0
#19 0x00007fffee8a9fd4 in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#20 0x00007ffff2cc6f8f in QEventDispatcherGlib::processEvents(QFlags) () from /usr/lib64/libQtCore.so.4
#21 0x00007ffff3a22d5e in ?? () from /usr/lib64/libQtGui.so.4
#22 0x00007ffff2c96cf2 in QEventLoop::processEvents(QFlags) () from /usr/lib64/libQtCore.so.4
#23 0x00007ffff2c96f47 in QEventLoop::exec(QFlags) () from /usr/lib64/libQtCore.so.4
#24 0x00007ffff3e48b76 in QDialog::exec() () from /usr/lib64/libQtGui.so.4
#25 0x000000000092ddba in ScoreView::elementPropertyAction (this=0x5793a40, cmd=..., e=0x5fe0400) at /home/collette/repositories/MuseScore/mscore/propertymenu.cpp:730
#26 0x0000000000690dcf in ScoreView::objectPopup (this=0x5793a40, pos=..., obj=0x5fe0400) at /home/collette/repositories/MuseScore/mscore/scoreview.cpp:1008
#27 0x000000000069be3d in ScoreView::contextPopup (this=0x5793a40, ev=0x5912b50) at /home/collette/repositories/MuseScore/mscore/scoreview.cpp:2934
#28 0x00000000006a95c9 in ContextTransition::onTransition (this=0x5796330, e=0x5fb2830) at /home/collette/repositories/MuseScore/mscore/scoreview.cpp:181
#29 0x00007ffff2cd2fa9 in QStateMachinePrivate::executeTransitionContent(QEvent*, QList const&) () from /usr/lib64/libQtCore.so.4
#30 0x00007ffff2cdc97b in QStateMachinePrivate::microstep(QEvent*, QList const&) () from /usr/lib64/libQtCore.so.4
#31 0x00007ffff2cda1a2 in QStateMachinePrivate::_q_process() () from /usr/lib64/libQtCore.so.4
#32 0x00007ffff2cdccfb in QStateMachinePrivate::handleFilteredEvent(QObject*, QEvent*) () from /usr/lib64/libQtCore.so.4
#33 0x00007ffff2cdcddd in QStateMachine::eventFilter(QObject*, QEvent*) () from /usr/lib64/libQtCore.so.4
#34 0x00007ffff2c98348 in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /usr/lib64/libQtCore.so.4
#35 0x00007ffff397fc8f in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib64/libQtGui.so.4
#36 0x00007ffff3984f4d in QApplication::notify(QObject*, QEvent*) () from /usr/lib64/libQtGui.so.4
#37 0x00007ffff2c981bc in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib64/libQtCore.so.4
#38 0x00007ffff39fc818 in ?? () from /usr/lib64/libQtGui.so.4
#39 0x00007ffff39fb67a in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib64/libQtGui.so.4
#40 0x00007ffff3a230d2 in ?? () from /usr/lib64/libQtGui.so.4
#41 0x00007fffee8a9bc3 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#42 0x00007fffee8a9f10 in ?? () from /lib64/libglib-2.0.so.0
#43 0x00007fffee8a9fd4 in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#44 0x00007ffff2cc6f8f in QEventDispatcherGlib::processEvents(QFlags) () from /usr/lib64/libQtCore.so.4
#45 0x00007ffff3a22d5e in ?? () from /usr/lib64/libQtGui.so.4
#46 0x00007ffff2c96cf2 in QEventLoop::processEvents(QFlags) () from /usr/lib64/libQtCore.so.4
#47 0x00007ffff2c96f47 in QEventLoop::exec(QFlags) () from /usr/lib64/libQtCore.so.4
#48 0x00007ffff2c9bcf5 in QCoreApplication::exec() () from /usr/lib64/libQtCore.so.4
#49 0x0000000000753588 in main (argc=1, av=0x7fffffffda28) at /home/collette/repositories/MuseScore/mscore/musescore.cpp:2450

Some outputs related to the painevent parameters:

(gdb) print cstring
$1 = 0
(gdb) print _dots[cstring]
Cannot access memory at address 0x0

YC