Application that crashed: umbrello
Version of the application: 2.3.2
KDE Version: 4.3.2 (KDE 4.3.2)
Qt Version: 4.5.2
Operating System: Linux 2.6.28-16-generic i686
Distribution: Ubuntu 9.04

What I was doing when the application crashed:
I was doing some operations on one file, then I went back with undo and then wanted to redo the operations again, I hit the redo button several times pretty fast and it crashed

 -- Backtrace:
Application: Umbrello UML Modeller (umbrello), signal: Segmentation fault
[KCrash Handler]
#6  0xb740675c in QUndoCommand::text (this=0x947f720) at ../../include/QtCore/../../src/corelib/tools/qstring.h:711
#7  0xb7406905 in QUndoStack::undoText (this=0x91fa148) at util/qundostack.cpp:797
#8  0xb7407b10 in QUndoStackPrivate::setIndex (this=0x91fa158, idx=16, clean=false) at util/qundostack.cpp:403
#9  0xb7407e3d in QUndoStack::redo (this=0x91fa148) at util/qundostack.cpp:687
#10 0xb741b903 in QUndoStack::qt_metacall (this=0x91fa148, _c=QMetaObject::InvokeMetaMethod, _id=9, _a=0xbf9e3e7c) at .moc/release-shared/moc_qundostack.cpp:100
#11 0xb7a18862 in KUndoStack::qt_metacall (this=0x91fa148, _c=QMetaObject::InvokeMetaMethod, _id=13, _a=0xbf9e3e7c) at /build/buildd/kde4libs-4.3.2/obj-i486-linux-gnu/kdeui/kundostack.moc:58
#12 0xb68d21b8 in QMetaObject::activate (sender=0x920f1b0, from_signal_index=5, to_signal_index=6, argv=0xbf9e3e7c) at kernel/qobject.cpp:3113
#13 0xb68d25f0 in QMetaObject::activate (sender=0x920f1b0, m=0xb75e8e48, from_local_signal_index=1, to_local_signal_index=2, argv=0xbf9e3e7c) at kernel/qobject.cpp:3207
#14 0xb6d796c1 in QAction::triggered (this=0x920f1b0, _t1=false) at .moc/release-shared/moc_qaction.cpp:236
#15 0xb6d7ac3f in QAction::activate (this=0x920f1b0, event=QAction::Trigger) at kernel/qaction.cpp:1160
#16 0xb7221602 in QToolButton::nextCheckState (this=0x0) at ../../include/QtGui/../../src/gui/kernel/qaction.h:203
#17 0xb713a003 in QAbstractButtonPrivate::click (this=0x934d620) at widgets/qabstractbutton.cpp:525
#18 0xb713a2d6 in QAbstractButton::mouseReleaseEvent (this=0x934d560, e=0xbf9e4488) at widgets/qabstractbutton.cpp:1115
#19 0xb7221afc in QToolButton::mouseReleaseEvent (this=0x934d560, e=0xbf9e4488) at widgets/qtoolbutton.cpp:709
#20 0xb6dd6973 in QWidget::event (this=0x934d560, event=0xbf9e4488) at kernel/qwidget.cpp:7549
#21 0xb713828e in QAbstractButton::event (this=0x934d560, e=0xbf9e4488) at widgets/qabstractbutton.cpp:1077
#22 0xb722452a in QToolButton::event (this=0x934d560, event=0xbf9e4488) at widgets/qtoolbutton.cpp:1151
#23 0xb6d7fd3c in QApplicationPrivate::notify_helper (this=0x91134c8, receiver=0x934d560, e=0xbf9e4488) at kernel/qapplication.cpp:4056
#24 0xb6d889b1 in QApplication::notify (this=0xbf9e5e08, receiver=0x934d560, e=0xbf9e4488) at kernel/qapplication.cpp:3758
#25 0xb797949d in KApplication::notify (this=0xbf9e5e08, receiver=0x934d560, event=0xbf9e4488) at /build/buildd/kde4libs-4.3.2/kdeui/kernel/kapplication.cpp:302
#26 0xb68bcbcb in QCoreApplication::notifyInternal (this=0xbf9e5e08, receiver=0x934d560, event=0xbf9e4488) at kernel/qcoreapplication.cpp:610
#27 0xb6d87a1e in QApplicationPrivate::sendMouseEvent (receiver=0x934d560, event=0xbf9e4488, alienWidget=0x934d560, nativeWidget=0x91c1270, buttonDown=0xb7601aa0, lastMouseReceiver=@0xb7601aa4)
    at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:216
#28 0xb6df7cce in QETWidget::translateMouseEvent (this=0x91c1270, event=0xbf9e5b1c) at kernel/qapplication_x11.cpp:4409
#29 0xb6df7085 in QApplication::x11ProcessEvent (this=0xbf9e5e08, event=0xbf9e5b1c) at kernel/qapplication_x11.cpp:3428
#30 0xb6e2237a in x11EventSourceDispatch (s=0x9116700, callback=0, user_data=0x0) at kernel/qguieventdispatcher_glib.cpp:146
#31 0xb5d90b88 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#32 0xb5d940eb in ?? () from /usr/lib/libglib-2.0.so.0
#33 0xb5d94268 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#34 0xb68e82f8 in QEventDispatcherGlib::processEvents (this=0x90f74d0, flags={i = -1080140584}) at kernel/qeventdispatcher_glib.cpp:327
#35 0xb6e21a75 in QGuiEventDispatcherGlib::processEvents (this=0x90f74d0, flags={i = -1080140536}) at kernel/qguieventdispatcher_glib.cpp:202
#36 0xb68bb1fa in QEventLoop::processEvents (this=0xbf9e5d80, flags={i = -1080140472}) at kernel/qeventloop.cpp:149
#37 0xb68bb642 in QEventLoop::exec (this=0xbf9e5d80, flags={i = -1080140408}) at kernel/qeventloop.cpp:201
#38 0xb68bdae9 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:888
#39 0xb6d7fbb7 in QApplication::exec () at kernel/qapplication.cpp:3525
#40 0x086f1985 in ?? ()
#41 0xb6218775 in __libc_start_main () from /lib/tls/i686/cmov/libc.so.6
#42 0x080729d1 in _start ()

Reported using DrKonqi