Version:           svn 1032389 (07.10.09) (using KDE 4.3.1)
OS:                Linux
Installed from:    Gentoo Packages

No idea how I triggered this, but it seems that you can hit this assertion:

Calling appendChild() on a null node does nothing.                                                                                                   
Calling appendChild() on a null node does nothing.                                                                                                   
Object::connect: No such signal QuickOpenWidgetDialog::scopesChanged( const QStringList& ) in /home/thorben/devel/src/kdevplatform/plugins/quickopen/quickopenplugin.cpp:812                                                                                                                              
Object::connect: No such signal QuickOpenWidgetDialog::itemsChanged( const QStringList& ) in /home/thorben/devel/src/kdevplatform/plugins/quickopen/quickopenplugin.cpp:813                                                                                                                               
ASSERT: "standardContext->smartRange()->document() == doc->textDocument()" in file /home/thorben/devel/src/kdevplatform/language/duchain/duchain.cpp, line 1457                                                                                                                                           

Program received signal SIGABRT, Aborted.
[Switching to Thread 0x7fb43e6c1750 (LWP 15205)]
0x00007fb439a10095 in raise () from /lib/libc.so.6
(gdb) r
The program being debugged has been started already.
Start it from the beginning? (y or n)               
Please answer y or n.                               
The program being debugged has been started already.
Start it from the beginning? (y or n) Please answer y or n.
The program being debugged has been started already.       
Start it from the beginning? (y or n)                      
Please answer y or n.                                      
The program being debugged has been started already.       
Start it from the beginning? (y or n)                      
Please answer y or n.                                      
The program being debugged has been started already.       
Start it from the beginning? (y or n) n                    
Program not restarted.                                     
(gdb) bt                                                   
#0  0x00007fb439a10095 in raise () from /lib/libc.so.6     
#1  0x00007fb439a114c0 in abort () from /lib/libc.so.6     
#2  0x00007fb43b4371c4 in qt_message_output () from /usr/lib64/qt4/libQtCore.so.4
#3  0x00007fb43b4372e0 in qFatal () from /usr/lib64/qt4/libQtCore.so.4           
#4  0x00007fb43822aa37 in KDevelop::DUChain::documentLoadedPrepare (this=0x18f93c0, doc=0x809bbb0)
    at /home/thorben/devel/src/kdevplatform/language/duchain/duchain.cpp:1457                     
#5  0x00007fb43822c4ad in KDevelop::DUChain::qt_metacall (this=0x18f93c0, _c=QMetaObject::InvokeMetaMethod, _id=6, _a=0x7fff35e21b00)
    at /home/thorben/devel/dbg/kdevplatform/language/duchain.moc:162                                                                 
#6  0x00007fb43b524094 in QMetaObject::activate () from /usr/lib64/qt4/libQtCore.so.4                                                
#7  0x00007fb43de55ced in KDevelop::IDocumentController::documentLoadedPrepare (this=0x1874de0, _t1=0x809bbb0)                       
    at /home/thorben/devel/src/kdevplatform/interfaces/idocumentcontroller.moc:256                                                   
#8  0x00007fb43de51b33 in KDevelop::IDocument::notifyLoaded (this=0x809bbb0) at /home/thorben/devel/src/kdevplatform/interfaces/idocument.cpp:119
#9  0x00007fb43db8adb1 in KDevelop::TextDocumentPrivate::slotDocumentLoaded (this=0x1f11ca40)                                                    
    at /home/thorben/devel/src/kdevplatform/shell/textdocument.cpp:154                                                                           
#10 0x00007fb43db8a37f in KDevelop::TextDocument::qt_metacall (this=0x809bb90, _c=QMetaObject::InvokeMetaMethod, _id=6, _a=0x7fff35e21cb0)       
    at /home/thorben/devel/src/kdevplatform/shell/textdocument.moc:88                                                                            
#11 0x00007fb43b524094 in QMetaObject::activate () from /usr/lib64/qt4/libQtCore.so.4                                                            
#12 0x00007fb43cd66b82 in KTextEditor::Document::textChanged () from /usr/lib/libktexteditor.so.4                                                
#13 0x00007fb4192e50ea in ?? () from /usr/lib64/kde4/katepart.so                                                                                 
#14 0x00007fb43d1b5067 in KParts::ReadOnlyPart::openUrl () from /usr/lib/libkparts.so.4                                                          
#15 0x00007fb43db876f7 in KDevelop::TextDocument::createViewWidget (this=0x809bb90, parent=0x5610b80)                                            
    at /home/thorben/devel/src/kdevplatform/shell/textdocument.cpp:239                                                                           
---Type <return> to continue, or q <return> to quit---                                                                                           
#16 0x00007fb43db89249 in KDevelop::TextView::createWidget (this=0x21e13970, parent=0x5610b80)                                                   
    at /home/thorben/devel/src/kdevplatform/shell/textdocument.cpp:522                                                                           
#17 0x00007fb437f388f6 in Sublime::View::widget (this=0x21e13970, parent=0x5610b80) at /home/thorben/devel/src/kdevplatform/sublime/view.cpp:82  
#18 0x00007fb437f3097a in Sublime::MainWindowPrivate::ViewCreator::operator() (this=0x7fff35e22850, index=0x17e1240)                             
    at /home/thorben/devel/src/kdevplatform/sublime/mainwindow_p.cpp:243                                                                         
#19 0x00007fb437f36717 in Sublime::Area::walkViewsInternal<Sublime::MainWindowPrivate::ViewCreator> (this=0x17e9c70, op=@0x7fff35e22850,         
    index=0x17e1240) at /home/thorben/devel/src/kdevplatform/sublime/areawalkers.h:32                                                            
#20 0x00007fb437f3549d in Sublime::Area::walkViews<Sublime::MainWindowPrivate::ViewCreator> (this=0x17e9c70, op=@0x7fff35e22850, index=0x17e1240)
    at /home/thorben/devel/src/kdevplatform/sublime/areawalkers.h:48                                                                             
#21 0x00007fb437f31898 in Sublime::MainWindowPrivate::viewAdded (this=0x1764be0, index=0x17e1240, view=0x21e13970)                               
    at /home/thorben/devel/src/kdevplatform/sublime/mainwindow_p.cpp:382                                                                         
#22 0x00007fb437f2b552 in Sublime::MainWindow::qt_metacall (this=0x17862b0, _c=QMetaObject::InvokeMetaMethod, _id=10, _a=0x7fff35e22a10)         
    at /home/thorben/devel/src/kdevplatform/sublime/mainwindow.moc:109                                                                           
#23 0x00007fb43db5ca4f in KDevelop::MainWindow::qt_metacall (this=0x17862b0, _c=QMetaObject::InvokeMetaMethod, _id=60, _a=0x7fff35e22a10)        
    at /home/thorben/devel/src/kdevplatform/shell/mainwindow.moc:83                                                                              
#24 0x00007fb43b524094 in QMetaObject::activate () from /usr/lib64/qt4/libQtCore.so.4                                                            
#25 0x00007fb437f1a90f in Sublime::Area::viewAdded (this=0x17e9c70, _t1=0x17e1240, _t2=0x21e13970)                                               
    at /home/thorben/devel/src/kdevplatform/sublime/area.moc:109                                                                                 
#26 0x00007fb437f18b03 in Sublime::Area::addView (this=0x17e9c70, view=0x21e13970, index=0x17e1240)                                              
    at /home/thorben/devel/src/kdevplatform/sublime/area.cpp:169                                                                                 
#27 0x00007fb437f18bb4 in Sublime::Area::addView (this=0x17e9c70, view=0x21e13970, after=0x54af2d0)                                              
    at /home/thorben/devel/src/kdevplatform/sublime/area.cpp:182                                                                                 
---Type <return> to continue, or q <return> to quit---                                                                                           
#28 0x00007fb43db911ef in KDevelop::DocumentControllerPrivate::openDocumentInternal (this=0x1874e90, doc=0x809bbb0, range=@0x7fff35e231e0,       
    activationParams={i = 0}) at /home/thorben/devel/src/kdevplatform/shell/documentcontroller.cpp:328                                           
#29 0x00007fb43db90b23 in KDevelop::DocumentControllerPrivate::openDocumentInternal (this=0x1874e90, inputUrl=@0x7fff35e23200,                   
    prefName=@0x7fff35e23190, range=@0x7fff35e231e0, activationParams={i = 0})                                                                   
    at /home/thorben/devel/src/kdevplatform/shell/documentcontroller.cpp:256                                                                     
#30 0x00007fb43db8cfaf in KDevelop::DocumentController::openDocument (this=0x1874de0, inputUrl=@0x7fff35e23200, range=@0x7fff35e231e0,           
    activationParams={i = 0}) at /home/thorben/devel/src/kdevplatform/shell/documentcontroller.cpp:522                                           
#31 0x00007fb41dbef0fa in ProjectFileData::execute (this=0x260d570)                                                                              
    at /home/thorben/devel/src/kdevplatform/plugins/quickopen/projectfilequickopen.cpp:54                                                        
#32 0x00007fb41dbebadc in QuickOpenModel::execute (this=0x2715830, index=@0x7fff35e235a0, filterText=@0x7fff35e23330)                            
    at /home/thorben/devel/src/kdevplatform/plugins/quickopen/quickopenmodel.cpp:412                                                             
#33 0x00007fb41dbdbeec in QuickOpenWidget::eventFilter (this=0x4bd8e90, watched=0x2674e70, event=0x7fff35e23a90)                                 
    at /home/thorben/devel/src/kdevplatform/plugins/quickopen/quickopenplugin.cpp:627                                                            
#34 0x00007fb43b511ca6 in QCoreApplicationPrivate::sendThroughObjectEventFilters () from /usr/lib64/qt4/libQtCore.so.4                           
#35 0x00007fb43a6661cc in QApplicationPrivate::notify_helper () from /usr/lib64/qt4/libQtGui.so.4                                                
#36 0x00007fb43a66c9b3 in QApplication::notify () from /usr/lib64/qt4/libQtGui.so.4                                                              
#37 0x00007fb43bc51b16 in KApplication::notify () from /usr/lib/libkdeui.so.5                                                                    
#38 0x00007fb43b51291b in QCoreApplication::notifyInternal () from /usr/lib64/qt4/libQtCore.so.4                                                 
#39 0x00007fb43a6e867d in ?? () from /usr/lib64/qt4/libQtGui.so.4                                                                                
#40 0x00007fb43a6eb3bf in ?? () from /usr/lib64/qt4/libQtGui.so.4                                                                                
#41 0x00007fb43a6c6d58 in QApplication::x11ProcessEvent () from /usr/lib64/qt4/libQtGui.so.4
#42 0x00007fb43a6ec1c4 in ?? () from /usr/lib64/qt4/libQtGui.so.4
---Type <return> to continue, or q <return> to quit---
#43 0x00007fb434dee96d in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#44 0x00007fb434df2128 in ?? () from /usr/lib/libglib-2.0.so.0
#45 0x00007fb434df2250 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#46 0x00007fb43b5370b6 in QEventDispatcherGlib::processEvents () from /usr/lib64/qt4/libQtCore.so.4
#47 0x00007fb43a6eba6e in ?? () from /usr/lib64/qt4/libQtGui.so.4
#48 0x00007fb43b511342 in QEventLoop::processEvents () from /usr/lib64/qt4/libQtCore.so.4
#49 0x00007fb43b5114dd in QEventLoop::exec () from /usr/lib64/qt4/libQtCore.so.4
#50 0x00007fb43b5132c9 in QCoreApplication::exec () from /usr/lib64/qt4/libQtCore.so.4

#51 0x0000000000407ff9 in main (argc=1, argv=0x7fff35e26e38) at /home/thorben/devel/src/kdevelop/app/main.cpp:181
(gdb)