Crash when editing the drumset

I click on "Edit drumset", select "Open Hi-Hat" and change "Staff line" from 1 to -1. Clicking on "OK" crashes MuseScore (2RC) with the below stack.
Process: mscore [825]
Path: /Applications/MuseScore 2.app/Contents/MacOS/mscore
Identifier: org.musescore.MuseScore
Version: 2.0 (2.0.0)
Code Type: X86-64 (Native)
Parent Process: ??? [1]
Responsible: mscore [825]
User ID: 501

Date/Time: 2015-03-14 17:33:48.318 +0100
OS Version: Mac OS X 10.10.2 (14C1510)
Report Version: 11
Anonymous UUID: CDF19024-0A72-D795-1A08-2BB75B307C61

Time Awake Since Boot: 8200 seconds

Crashed Thread: 0 Dispatch queue: com.apple.main-thread

Exception Type: EXC_BAD_ACCESS (SIGSEGV)
Exception Codes: KERN_INVALID_ADDRESS at 0x00000000e838bdc1

VM Regions Near 0xe838bdc1:
-->
__TEXT 000000010bd58000-000000010c88b000 [ 11.2M] r-x/rwx SM=COW /Applications/MuseScore 2.app/Contents/MacOS/mscore

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0 org.qt-project.QtCore 0x000000010d011ffa QByteArray::QByteArray(int, Qt::Initialization) + 58
1 org.qt-project.QtCore 0x000000010d0a4941 QString::toLatin1_helper(QString const&) + 49
2 org.musescore.MuseScore 0x000000010be04f6b Ms::DrumTools::updateDrumset() + 555
3 org.musescore.MuseScore 0x000000010be0528e Ms::DrumTools::editDrumset() + 110
4 org.qt-project.QtCore 0x000000010d2497ab QMetaObject::activate(QObject*, int, int, void**) + 2987
5 org.qt-project.QtWidgets 0x000000010f808f40 QAbstractButton::clicked(bool) + 64
6 org.qt-project.QtWidgets 0x000000010f562e2a 0x10f44d000 + 1138218
7 org.qt-project.QtWidgets 0x000000010f562ca7 0x10f44d000 + 1137831
8 org.qt-project.QtWidgets 0x000000010f563cae QAbstractButton::mouseReleaseEvent(QMouseEvent*) + 270
9 org.qt-project.QtWidgets 0x000000010f62a42f QToolButton::mouseReleaseEvent(QMouseEvent*) + 15
10 org.qt-project.QtWidgets 0x000000010f4bda1c QWidget::event(QEvent*) + 1628
11 org.qt-project.QtWidgets 0x000000010f563a03 QAbstractButton::event(QEvent*) + 179
12 org.qt-project.QtWidgets 0x000000010f62a9f4 QToolButton::event(QEvent*) + 324
13 org.qt-project.QtWidgets 0x000000010f47e32b QApplicationPrivate::notify_helper(QObject*, QEvent*) + 251
14 org.qt-project.QtWidgets 0x000000010f481b8d QApplication::notify(QObject*, QEvent*) + 9485
15 org.qt-project.QtCore 0x000000010d216d83 QCoreApplication::notifyInternal(QObject*, QEvent*) + 115
16 org.qt-project.QtWidgets 0x000000010f47ecab QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer&, bool) + 987
17 org.qt-project.QtWidgets 0x000000010f4d8ab1 0x10f44d000 + 572081
18 org.qt-project.QtWidgets 0x000000010f4d7cef 0x10f44d000 + 568559
19 org.qt-project.QtWidgets 0x000000010f47e32b QApplicationPrivate::notify_helper(QObject*, QEvent*) + 251
20 org.qt-project.QtWidgets 0x000000010f481648 QApplication::notify(QObject*, QEvent*) + 8136
21 org.qt-project.QtCore 0x000000010d216d83 QCoreApplication::notifyInternal(QObject*, QEvent*) + 115
22 org.qt-project.QtGui 0x000000010d59ba6d QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) + 2189
23 org.qt-project.QtGui 0x000000010d59a983 QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) + 131
24 org.qt-project.QtGui 0x000000010d5882da QWindowSystemInterface::sendWindowSystemEvents(QFlags) + 346
25 libqcocoa.dylib 0x00000001137f9411 0x1137d8000 + 136209
26 com.apple.CoreFoundation 0x00007fff8646f681 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17
27 com.apple.CoreFoundation 0x00007fff8646180d __CFRunLoopDoSources0 + 269
28 com.apple.CoreFoundation 0x00007fff86460e3f __CFRunLoopRun + 927
29 com.apple.CoreFoundation 0x00007fff86460858 CFRunLoopRunSpecific + 296
30 com.apple.HIToolbox 0x00007fff9351faef RunCurrentEventLoopInMode + 235
31 com.apple.HIToolbox 0x00007fff9351f76e ReceiveNextEventCommon + 179
32 com.apple.HIToolbox 0x00007fff9351f6ab _BlockUntilNextEventMatchingListInModeWithFilter + 71
33 com.apple.AppKit 0x00007fff90ff4f81 _DPSNextEvent + 964
34 com.apple.AppKit 0x00007fff90ff4730 -[NSApplication nextEventMatchingMask:untilDate:inMode:dequeue:] + 194
35 com.apple.AppKit 0x00007fff90fe8593 -[NSApplication run] + 594
36 libqcocoa.dylib 0x00000001137f82fd 0x1137d8000 + 131837
37 org.qt-project.QtCore 0x000000010d21437d QEventLoop::exec(QFlags) + 381
38 org.qt-project.QtCore 0x000000010d21735a QCoreApplication::exec() + 346
39 org.musescore.MuseScore 0x000000010c0b1033 main + 16739
40 org.musescore.MuseScore 0x000000010bd63cb4 start + 52