Confirmed in current trunk too.

@FiNeX: can you provide a better backtrace? Thanks

Application: Konqueror (kdeinit4), signal: Segmentation fault
[Current thread is 0 (LWP 9778)]

Thread 2 (Thread 0x7f06502e6910 (LWP 9783)):
#0  0x00007f066996405d in pthread_cond_timedwait@@GLIBC_2.3.2 () from /lib/libpthread.so.0
#1  0x00007f0669bd32b2 in QWaitCondition::wait () from /usr/lib/libQtCore.so.4
#2  0x00007f0669bc9412 in ?? () from /usr/lib/libQtCore.so.4
#3  0x00007f0669bd2285 in ?? () from /usr/lib/libQtCore.so.4
#4  0x00007f066995f57a in start_thread () from /lib/libpthread.so.0
#5  0x00007f066646316d in clone () from /lib/libc.so.6
#6  0x0000000000000000 in ?? ()

Thread 1 (Thread 0x7f066a18e760 (LWP 9778)):
[KCrash Handler]
#5  0x00007f066744d311 in QTabWidget::qt_metacall () from /usr/lib/libQtGui.so.4
#6  0x00007f06682275d5 in KTabWidget::qt_metacall (this=0x21d2870, _c=QMetaObject::InvokeMetaMethod, _id=-2223672, _a=0x7fff59fd4fc0) at /home/test/KDE4/src/build/kdelibs/kdeui/ktabwidget.moc:124
#7  0x00007f065d0511a5 in KonqFrameTabs::qt_metacall (this=0x21d2870, _c=QMetaObject::InvokeMetaMethod, _id=-2223672, _a=0x7fff59fd4fc0)
    at /home/test/KDE4/src/build/kdebase/apps/konqueror/src/konqtabs.moc:94
#8  0x00007f0669cccdec in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#9  0x00007f065d0460ca in KonqFrame::eventFilter (this=0x21cf230, ev=<value optimized out>) at /home/test/KDE4/src/kdebase/apps/konqueror/src/konqframe.cpp:175
#10 0x00007f0669cb7007 in QCoreApplicationPrivate::sendThroughObjectEventFilters () from /usr/lib/libQtCore.so.4
#11 0x00007f066703166c in QApplicationPrivate::notify_helper () from /usr/lib/libQtGui.so.4
#12 0x00007f0667039483 in QApplication::notify () from /usr/lib/libQtGui.so.4
#13 0x00007f0668137f36 in KApplication::notify (this=0x7fff59fd7730, receiver=0x220e760, event=0x7fff59fd5460) at /home/test/KDE4/src/kdelibs/kdeui/kernel/kapplication.cpp:302
#14 0x00007f0669cb7cec in QCoreApplication::notifyInternal () from /usr/lib/libQtCore.so.4
#15 0x00007f06670c0fca in ?? () from /usr/lib/libQtGui.so.4
#16 0x00007f06670c3511 in ?? () from /usr/lib/libQtGui.so.4
#17 0x00007f066709ca44 in QApplication::x11ProcessEvent () from /usr/lib/libQtGui.so.4
#18 0x00007f06670c4e6c in ?? () from /usr/lib/libQtGui.so.4
#19 0x00007f0665aeddbe in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#20 0x00007f0665af1568 in g_main_context_iterate () from /usr/lib/libglib-2.0.so.0
#21 0x00007f0665af1690 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#22 0x00007f0669ce01b6 in QEventDispatcherGlib::processEvents () from /usr/lib/libQtCore.so.4
#23 0x00007f06670c464e in ?? () from /usr/lib/libQtGui.so.4
#24 0x00007f0669cb65f2 in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#25 0x00007f0669cb69c4 in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#26 0x00007f0669cb8b79 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#27 0x00007f065d0b5653 in kdemain (argc=<value optimized out>, argv=<value optimized out>) at /home/test/KDE4/src/kdebase/apps/konqueror/src/konqmain.cpp:257
#28 0x00000000004070be in launch (argc=4, _name=<value optimized out>, args=<value optimized out>, cwd=<value optimized out>, envc=32, envs=<value optimized out>, reset_env=true, tty=0x0,
    avoid_loops=false, startup_id_str=0x1919790 "blackhole;1250449488;49583;4479_TIME41236125") at /home/test/KDE4/src/kdelibs/kinit/kinit.cpp:705
#29 0x0000000000407ccd in handle_launcher_request (sock=19, who=<value optimized out>) at /home/test/KDE4/src/kdelibs/kinit/kinit.cpp:1197
#30 0x000000000040816b in handle_requests (waitForPid=0) at /home/test/KDE4/src/kdelibs/kinit/kinit.cpp:1381
#31 0x0000000000408962 in main (argc=1, argv=<value optimized out>, envp=<value optimized out>) at /home/test/KDE4/src/kdelibs/kinit/kinit.cpp:1825

Weird.. you don't have the KConfig calls..

*** Bug 205287 has been marked as a duplicate of this bug. ***

*** Bug 205969 has been marked as a duplicate of this bug. ***

*** Bug 207753 has been marked as a duplicate of this bug. ***

*** Bug 210182 has been marked as a duplicate of this bug. ***

*** Bug 213795 has been marked as a duplicate of this bug. ***

*** Bug 214360 has been marked as a duplicate of this bug. ***

*** Bug 217568 has been marked as a duplicate of this bug. ***

*** Bug 222053 has been marked as a duplicate of this bug. ***

==17290== Invalid read of size 4
==17290==    at 0x5C2FB12: QTabWidget::qt_metacall(QMetaObject::Call, int, void**) (moc_qtabwidget.cpp:143)
==17290==    by 0x4B36AE9: KTabWidget::qt_metacall(QMetaObject::Call, int, void**) (ktabwidget.moc:128)
==17290==    by 0x40D3F89: KonqFrameTabs::qt_metacall(QMetaObject::Call, int, void**) (konqtabs.moc:100)
==17290==    by 0x52257B5: QMetaObject::metacall(QObject*, QMetaObject::Call, int, void**) (qmetaobject.cpp:237)
==17290==    by 0x5237979: QMetaObject::activate(QObject*, QMetaObject const*, int, void**) (qobject.cpp:3291)
==17290==    by 0x40D0236: KonqFrameContainer::ctrlTabPressed() (konqframecontainer.moc:88)
==17290==    by 0x40CD0CC: KonqFrame::eventFilter(QObject*, QEvent*) (konqframe.cpp:180)
==17290==    by 0x521EBC4: QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) (qcoreapplication.cpp:819)
==17290==    by 0x571EE41: QApplicationPrivate::notify_helper(QObject*, QEvent*) (qapplication.cpp:4238)
==17290==    by 0x571CDD7: QApplication::notify(QObject*, QEvent*) (qapplication.cpp:3720)
==17290==    by 0x4A1E472: KApplication::notify(QObject*, QEvent*) (kapplication.cpp:302)
==17290==    by 0x521E91B: QCoreApplication::notifyInternal(QObject*, QEvent*) (qcoreapplication.cpp:704)
==17290==  Address 0x1c is not stack'd, malloc'd or (recently) free'd


That konqframe.cpp:180 cast looks really ugly...

Yep, and it's the problem... That bit of code is from 2001, and is ultra-brittle, so no wonder it broke.

My naive attempt at fixing this is this:
--- src/konqframe.cpp   (revision 1066847)                         
+++ src/konqframe.cpp   (working copy)                             
@@ -177,7 +177,17 @@                                               
       QKeyEvent * keyEv = static_cast<QKeyEvent*>(ev);            
       if ((keyEv->key()==Qt::Key_Tab) && (keyEv->modifiers()==Qt::ControlModifier))
       {                                                                            
-         emit ((KonqFrameContainer*)parent())->ctrlTabPressed();                   
+         // Find the container frame..                                             
+         KonqFrameContainerBase* cont;                                             
+         for (cont = parentContainer(); cont; cont = cont->parentContainer()) {    
+                                                                                   
+            kDebug() << cont << frameTypeToString(cont->frameType());              
+            if (cont->frameType() == KonqFrameBase::Container)                     
+               break;                                                              
+         }                                                                         
+                                                                                   
+         if (cont)                                                                 
+            emit static_cast<KonqFrameContainer*>(cont)->ctrlTabPressed();         
          return true;                                                              
       }                                                                            
    }                                                                               

which sort of works --- it switches between views within a single tab; but I think I better consult dfaure for his opinion, since I don't know the class hierarchy well here at all.

SVN commit 1076829 by dfaure:

Rewrite the Ctrl+Tab handling with a single event filter; no more signals and unchecked casts (crash!).
BUG: 203809
Fixed for: 4.4


 M  +2 -16     konqframe.cpp  
 M  +0 -6      konqframe.h  
 M  +0 -2      konqframecontainer.h  
 M  +6 -1      konqmainwindow.cpp  
 M  +0 -2      konqtabs.h  
 M  +0 -4      konqviewmanager.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=1076829

SVN commit 1078192 by dfaure:

Backport 1076829: Fix crash on Ctrl+Tab.
Fixed for: 4.3.5
CCBUG: 203809


 M  +2 -16     konqframe.cpp  
 M  +0 -6      konqframe.h  
 M  +0 -2      konqframecontainer.h  
 M  +6 -1      konqmainwindow.cpp  
 M  +0 -2      konqtabs.h  
 M  +0 -4      konqviewmanager.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=1078192

*** Bug 222299 has been marked as a duplicate of this bug. ***

For the record, I just fixed Ctrl+Tab handling so that it behaves as expected (even with splitted views and tabs) for KDE-4.5.


SVN commit 1110338 by dfaure:

Fix Ctrl+Tab handling, especially for the interesting case of splitted views in tabs:
* Rewrite chooseNextView to be deterministic rather than rely on a map sorted on pointer addresses
* Remove the fix for bug 67956 from KonqViewManager::doSetActivePart and fix that bug again at the right
level: by removing the setActivePart from KonqView::changePart, which I added in 2000 with the comment
"just in case". Heh.
* Fix another setActivePart in KonqMainWindow::slotPartChanged which also would trigger bug 67956.
* Fix the Ctrl+Tab event filter so that it doesn't let it propagate to QTabWidget (which also handles that shortcut)
* Add unittests for 67956 (with and without the option "tabs in front"); add unittests for Ctrl+Tab.

*** Bug 233140 has been marked as a duplicate of this bug. ***

*** Bug 234429 has been marked as a duplicate of this bug. ***