Hmm, I'm re-opening this one as I can still reproduce a crash that looks related (let me know if I should create a new backtrace for it). Create a non-utf8 file (I've used latin1 with german umlauts), then open it in kdevelop. 

First problem: The same dialog twice and it seems the view is also opened twice. Now close the document again. 

Second problem: Try to open the same document a second time, you again get both messageboxes, but after seeing the second kdevelop will crash with this:

#0  0xb5511f2d in QFlags<Qt::WindowType>::operator& (this=0x8, f=Qt::WindowType_Mask)
    at ../../include/QtCore/../../../../kde-qt/src/corelib/global/qglobal.h:2181     
#1  0xb5511f68 in QWidget::windowType (this=0xc575a70) at ../../include/QtGui/../../../../kde-qt/src/gui/kernel/qwidget.h:914
#2  0xb5585b53 in QWidgetPrivate::init (this=0xd0f8358, parentWidget=0xc575a70, f=...) at /home/andreas/src/kde-qt/src/gui/kernel/qwidget.cpp:1122
#3  0xb5589359 in QWidget (this=0xd0bf570, parent=0xc575a70, f=...) at /home/andreas/src/kde-qt/src/gui/kernel/qwidget.cpp:1007                   
---Type <return> to continue, or q <return> to quit---                                                                                            
#4  0xb71f84e7 in View (this=0xd0bf570, parent=0xc575a70) at /home/andreas/src/kdelibs/interfaces/ktexteditor/ktexteditor.cpp:260                 
#5  0xa3ff23f9 in KateView (this=0xd0bf570, doc=0xcec6bb8, parent=0xc575a70) at /home/andreas/src/kdelibs/kate/view/kateview.cpp:123              
#6  0xa3f3bdde in KateDocument::createView (this=0xcec6bb8, parent=0xc575a70) at /home/andreas/src/kdelibs/kate/document/katedocument.cpp:340     
#7  0xb75a0fb0 in KDevelop::TextDocument::createViewWidget (this=0xcda0548, parent=0xc575a70)                                                     
    at /home/andreas/src/kdevplatform/shell/textdocument.cpp:268                                                                                  
#8  0xb759f45f in KDevelop::TextView::createWidget (this=0xce0d008, parent=0xc575a70) at /home/andreas/src/kdevplatform/shell/textdocument.cpp:522
#9  0xb49bc20c in Sublime::View::widget (this=0xce0d008, parent=0xc575a70) at /home/andreas/src/kdevplatform/sublime/view.cpp:82                  
#10 0xb49b567f in Sublime::MainWindowPrivate::ViewCreator::operator() (this=0xbff98808, index=0x99396a0)                                          
    at /home/andreas/src/kdevplatform/sublime/mainwindow_p.cpp:243                                                                                
#11 0xb49bafb6 in Sublime::Area::walkViewsInternal<Sublime::MainWindowPrivate::ViewCreator> (this=0x9962f88, op=..., index=0x99396a0)             
    at /home/andreas/src/kdevplatform/sublime/areawalkers.h:32                                                                                    
#12 0xb49bb08b in Sublime::Area::walkViews<Sublime::MainWindowPrivate::ViewCreator> (this=0x9962f88, op=..., index=0x99396a0)                     
    at /home/andreas/src/kdevplatform/sublime/areawalkers.h:48                                                                                    
#13 0xb49b5a6b in Sublime::MainWindowPrivate::viewAdded (this=0x994b168, index=0x99396a0, view=0xce0d008)                                         
    at /home/andreas/src/kdevplatform/sublime/mainwindow_p.cpp:389                                                                                
#14 0xb49aed5c in Sublime::MainWindow::qt_metacall (this=0x9948528, _c=QMetaObject::InvokeMetaMethod, _id=11, _a=0xbff98968)                      
    at /home/andreas/src/build/kdevplatform/sublime/mainwindow.moc:118                                                                            
#15 0xb7573cbc in KDevelop::MainWindow::qt_metacall (this=0x9948528, _c=QMetaObject::InvokeMetaMethod, _id=61, _a=0xbff98968)                     
    at /home/andreas/src/build/kdevplatform/shell/mainwindow.moc:91                                                                               
#16 0xb62a3b3b in QMetaObject::metacall (object=0x9948528, cl=QMetaObject::InvokeMetaMethod, idx=61, argv=0xbff98968)                             
    at /home/andreas/src/kde-qt/src/corelib/kernel/qmetaobject.cpp:237                                                                            
#17 0xb62b84de in QMetaObject::activate (sender=0x9962f88, m=0xb49d57a0, local_signal_index=0, argv=0xbff98968)                                   
    at /home/andreas/src/kde-qt/src/corelib/kernel/qobject.cpp:3282                                                                               
#18 0xb499d66b in Sublime::Area::viewAdded (this=0x9962f88, _t1=0x99396a0, _t2=0xce0d008) at /home/andreas/src/build/kdevplatform/sublime/area.moc:115
#19 0xb499f653 in Sublime::Area::addView (this=0x9962f88, view=0xce0d008, index=0x99396a0) at /home/andreas/src/kdevplatform/sublime/area.cpp:169     
#20 0xb499f6fa in Sublime::Area::addView (this=0x9962f88, view=0xce0d008, after=0x0) at /home/andreas/src/kdevplatform/sublime/area.cpp:182           
#21 0xb75a8056 in KDevelop::DocumentControllerPrivate::openDocumentInternal (this=0x9a5ca20, doc=0xcda0558, range=..., activationParams=...)
    at /home/andreas/src/kdevplatform/shell/documentcontroller.cpp:347
#22 0xb75a9770 in KDevelop::DocumentControllerPrivate::openDocumentInternal (this=0x9a5ca20, inputUrl=..., prefName=..., range=..., encoding=...,
    activationParams=...) at /home/andreas/src/kdevplatform/shell/documentcontroller.cpp:275
#23 0xb75a2c9e in KDevelop::DocumentController::openDocument (this=0x9a5c970, inputUrl=..., range=..., activationParams=...)
    at /home/andreas/src/kdevplatform/shell/documentcontroller.cpp:541
#24 0xa75584c4 in FileManager::openFile (this=0xab7eba8, file=...) at /home/andreas/src/kdevplatform/plugins/filemanager/filemanager.cpp:74
#25 0xa7558571 in FileManager::qt_metacall (this=0xab7eba8, _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0xbff98eac)
    at /home/andreas/src/build/kdevplatform/plugins/filemanager/filemanager.moc:77
#26 0xb62a3b3b in QMetaObject::metacall (object=0xab7eba8, cl=QMetaObject::InvokeMetaMethod, idx=27, argv=0xbff98eac)
    at /home/andreas/src/kde-qt/src/corelib/kernel/qmetaobject.cpp:237
#27 0xb62b84de in QMetaObject::activate (sender=0xacf5648, m=0xb4d17454, local_signal_index=7, argv=0xbff98eac)
    at /home/andreas/src/kde-qt/src/corelib/kernel/qobject.cpp:3282
#28 0xb4cb6cd3 in KDirOperator::fileSelected (this=0xacf5648, _t1=...) at /home/andreas/src/build/kdelibs/kfile/kdiroperator.moc:322
#29 0xb4cb7859 in KDirOperator::selectFile (this=0xacf5648, item=...) at /home/andreas/src/kdelibs/kfile/kdiroperator.cpp:1718
#30 0xb4cb79c3 in KDirOperator::Private::_k_slotActivated (this=0xa890180, index=...) at /home/andreas/src/kdelibs/kfile/kdiroperator.cpp:2365
#31 0xb4cc30e5 in KDirOperator::qt_metacall (this=0xacf5648, _c=QMetaObject::InvokeMetaMethod, _id=59, _a=0xbff9906c)
    at /home/andreas/src/build/kdelibs/kfile/kdiroperator.moc:251
#32 0xb62a3b3b in QMetaObject::metacall (object=0xacf5648, cl=QMetaObject::InvokeMetaMethod, idx=86, argv=0xbff9906c)
    at /home/andreas/src/kde-qt/src/corelib/kernel/qmetaobject.cpp:237
#33 0xb62b84de in QMetaObject::activate (sender=0xac376c0, m=0xb602fb84, local_signal_index=3, argv=0xbff9906c)
    at /home/andreas/src/kde-qt/src/corelib/kernel/qobject.cpp:3282
#34 0xb5bdf0fc in QAbstractItemView::activated (this=0xac376c0, _t1=...) at .moc/debug-shared/moc_qabstractitemview.cpp:345
#35 0xb5be52af in QAbstractItemView::mouseReleaseEvent (this=0xac376c0, event=0xbff99d94)
    at /home/andreas/src/kde-qt/src/gui/itemviews/qabstractitemview.cpp:1761
#36 0xb5c3a1da in QTreeView::mouseReleaseEvent (this=0xac376c0, event=0xbff99d94) at /home/andreas/src/kde-qt/src/gui/itemviews/qtreeview.cpp:1822
#37 0xb558012b in QWidget::event (this=0xac376c0, event=0xbff99d94) at /home/andreas/src/kde-qt/src/gui/kernel/qwidget.cpp:7973
#38 0xb5a5f740 in QFrame::event (this=0xac376c0, e=0xbff99d94) at /home/andreas/src/kde-qt/src/gui/widgets/qframe.cpp:557
#39 0xb5b15faf in QAbstractScrollArea::viewportEvent (this=0xac376c0, e=0xbff99d94)
    at /home/andreas/src/kde-qt/src/gui/widgets/qabstractscrollarea.cpp:1032
#40 0xb5bea0f5 in QAbstractItemView::viewportEvent (this=0xac376c0, event=0xbff99d94)
    at /home/andreas/src/kde-qt/src/gui/itemviews/qabstractitemview.cpp:1589
#41 0xb5c3723b in QTreeView::viewportEvent (this=0xac376c0, event=0xbff99d94) at /home/andreas/src/kde-qt/src/gui/itemviews/qtreeview.cpp:1250
#42 0xb5b194f4 in QAbstractScrollAreaPrivate::viewportEvent (this=0xab38628, event=0xbff99d94)
    at /home/andreas/src/kde-qt/src/gui/widgets/qabstractscrollarea_p.h:100
#43 0xb5b19522 in QAbstractScrollAreaFilter::eventFilter (this=0xa9c61e8, o=0xab38a18, e=0xbff99d94)
---Type <return> to continue, or q <return> to quit---
    at /home/andreas/src/kde-qt/src/gui/widgets/qabstractscrollarea_p.h:116
#44 0xb6299caa in QCoreApplicationPrivate::sendThroughObjectEventFilters (this=0x9800758, receiver=0xab38a18, event=0xbff99d94)
    at /home/andreas/src/kde-qt/src/corelib/kernel/qcoreapplication.cpp:819
#45 0xb5502de1 in QApplicationPrivate::notify_helper (this=0x9800758, receiver=0xab38a18, e=0xbff99d94)
    at /home/andreas/src/kde-qt/src/gui/kernel/qapplication.cpp:4238
#46 0xb5503cec in QApplication::notify (this=0xbff9a6a0, receiver=0xab38a18, e=0xbff99d94)
    at /home/andreas/src/kde-qt/src/gui/kernel/qapplication.cpp:3822
#47 0xb665a41d in KApplication::notify (this=0xbff9a6a0, receiver=0xab38a18, event=0xbff99d94)
    at /home/andreas/src/kdelibs/kdeui/kernel/kapplication.cpp:302
#48 0xb629c1ec in QCoreApplication::notifyInternal (this=0xbff9a6a0, receiver=0xab38a18, event=0xbff99d94)
    at /home/andreas/src/kde-qt/src/corelib/kernel/qcoreapplication.cpp:704
#49 0xb5516b43 in QCoreApplication::sendSpontaneousEvent (receiver=0xab38a18, event=0xbff99d94)
    at ../../include/QtCore/../../../../kde-qt/src/corelib/kernel/qcoreapplication.h:218
#50 0xb5509e12 in QApplicationPrivate::sendMouseEvent (receiver=0xab38a18, event=0xbff99d94, alienWidget=0xab38a18, nativeWidget=0xc0f6e70,
    buttonDown=0xb6046380, lastMouseReceiver=..., spontaneous=true) at /home/andreas/src/kde-qt/src/gui/kernel/qapplication.cpp:2954
#51 0xb55bfcb8 in QETWidget::translateMouseEvent (this=0xc0f6e70, event=0xbff9a330) at /home/andreas/src/kde-qt/src/gui/kernel/qapplication_x11.cpp:4368
#52 0xb55c0d47 in QApplication::x11ProcessEvent (this=0xbff9a6a0, event=0xbff9a330) at /home/andreas/src/kde-qt/src/gui/kernel/qapplication_x11.cpp:3379
#53 0xb55f43f7 in x11EventSourceDispatch (s=0x98039b0, callback=0, user_data=0x0)
    at /home/andreas/src/kde-qt/src/gui/kernel/qguieventdispatcher_glib.cpp:146
#54 0xb41f4e98 in g_main_context_dispatch () from /lib/libglib-2.0.so.0
#55 0xb41f8623 in ?? () from /lib/libglib-2.0.so.0