Right click on multiple selected staves make crashes

i'm using musescore c6cfc3f on kxstudio 12.04

1- Open musescore
2 choose two instruments (or a piano for example, because it has two staves)
3- make a selection on both staves
4- right-click on it
5- it crashes

here is the gdb backtrace output :

daeavelwyn@StudioCorei5:~/MuseScore/build.release/mscore$ gdb mscore
GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2.1) 7.4-2012.04
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
...
Reading symbols from /home/daeavelwyn/MuseScore/build.release/mscore/mscore...done.
(gdb) run
Starting program: /home/daeavelwyn/MuseScore/build.release/mscore/mscore
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[New Thread 0x7fffe7850700 (LWP 9877)]
false
QDateTime("") QDateTime("")
read shortcuts from <:/data/shortcuts.xml>
no audio driver found
ChordList::read failed:
QObject::connect: Cannot connect QState::entered() to (null)::start()
QObject::connect: Cannot connect QState::exited() to (null)::stop()
QObject::connect: Cannot connect QState::entered() to (null)::start()
QObject::connect: Cannot connect QState::exited() to (null)::stop()

Program received signal SIGSEGV, Segmentation fault.
Ms::Seq::stopNotes(int) () at /home/daeavelwyn/MuseScore/mscore/seq.cpp:1040
1040 _synti->allNotesOff(channel);
(gdb) backtrace
#0 Ms::Seq::stopNotes(int) () at /home/daeavelwyn/MuseScore/mscore/seq.cpp:1040
#1 0x0000000000655e08 in Ms::ScoreView::contextPopup(QContextMenuEvent*) () at /home/daeavelwyn/MuseScore/mscore/scoreview.cpp:3125
#2 0x00007ffff72a1bf8 in QStateMachinePrivate::executeTransitionContent(QEvent*, QList const&) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#3 0x00007ffff72aaeaf in QStateMachinePrivate::microstep(QEvent*, QList const&) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#4 0x00007ffff72ab263 in QStateMachinePrivate::_q_process() () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#5 0x00007ffff72ad5fa in QStateMachinePrivate::handleFilteredEvent(QObject*, QEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#6 0x00007ffff72ad6ed in QStateMachine::eventFilter(QObject*, QEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#7 0x00007ffff724dffd in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#8 0x00007ffff548ab1f in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Widgets.so.5
#9 0x00007ffff548f809 in QApplication::notify(QObject*, QEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Widgets.so.5
#10 0x00007ffff724ddd4 in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#11 0x00007ffff54e0c1a in ?? () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Widgets.so.5
#12 0x00007ffff54e2a70 in ?? () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Widgets.so.5
#13 0x00007ffff548ab54 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Widgets.so.5
#14 0x00007ffff548dfe6 in QApplication::notify(QObject*, QEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Widgets.so.5
#15 0x00007ffff724ddd4 in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#16 0x00007ffff6a7701b in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Gui.so.5
#17 0x00007ffff6a778ed in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Gui.so.5
#18 0x00007ffff6a60a98 in QWindowSystemInterface::sendWindowSystemEventsImplementation(QFlags) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Gui.so.5
#19 0x00007fffe848d940 in ?? () from /opt/Qt5.1.1/5.1.1/gcc_64/plugins/platforms/libqxcb.so
#20 0x00007fffef4a2d13 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#21 0x00007fffef4a3060 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#22 0x00007fffef4a3124 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007ffff7298314 in QEventDispatcherGlib::processEvents(QFlags) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#24 0x00007ffff724cb6b in QEventLoop::exec(QFlags) () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#25 0x00007ffff7250bbe in QCoreApplication::exec() () from /opt/Qt5.1.1/5.1.1/gcc_64/lib/libQt5Core.so.5
#26 0x0000000000623edf in main () at /home/daeavelwyn/MuseScore/mscore/musescore.cpp:5000