Crashing for me on Fedora 23 as well. I am using File, Open rather than the toolbar.

Are you by chance using Compiz as window manager? 

There seems to be a problem with Compiz and KDE applications at the moment:

https://git.reviewboard.kde.org/r/126397/

It looks like compiz is _not_ running, but kwin is running (see below).  I _do_ have the default Desktop Effects enabled.  Let me know if that answers your question properly.  

Also, there were a ton of kf5-5.17 updates this morning.  I'd be happy to try any work-arounds you might recommend.  

$ ps aux |grep -E 'compiz|kwin' |grep -v grep
user   2751  3.5  0.6 3166104 101660 ?      Sl   06:50   1:15 kwin_x11

Can you install debug packages and produce a dump that has more info?

debug packages for: Kate, Frameworks integration (KDEPlatformTheme.so) and Qt

Via drkonqi

Backtrace of the crash I experienced:

Application: Kate (kate), signal: Segmentation fault
Using host libthread_db library "/lib64/libthread_db.so.1".
84	T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
[Current thread is 1 (Thread 0x7fa074459900 (LWP 29659))]

Thread 3 (Thread 0x7fa05513d700 (LWP 29660)):
#0  0x00007fa06cd34ffd in poll () at ../sysdeps/unix/syscall-template.S:84
#1  0x00007fa069c49272 in _xcb_conn_wait (__timeout=-1, __nfds=1, __fds=0x7fa05513cbc0) at /usr/include/bits/poll2.h:46
#2  0x00007fa069c49272 in _xcb_conn_wait (c=c@entry=0x5612ce8370e0, cond=cond@entry=0x5612ce837120, vector=vector@entry=0x0, count=count@entry=0x0) at xcb_conn.c:459
#3  0x00007fa069c4aee7 in xcb_wait_for_event (c=0x5612ce8370e0) at xcb_in.c:693
#4  0x00007fa057b09da9 in QXcbEventReader::run() (this=0x5612ce84a130) at qxcbconnection.cpp:1254
#5  0x00007fa06d93d3ce in QThreadPrivate::start(void*) (arg=0x5612ce84a130) at thread/qthread_unix.cpp:331
#6  0x00007fa06aef960a in start_thread (arg=0x7fa05513d700) at pthread_create.c:334
#7  0x00007fa06cd40a9d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7fa046f47700 (LWP 29661)):
#0  0x00007fa06aefeb10 in pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007fa04a7fc2fa in radeon_drm_cs_emit_ioctl (mtx=0x5612cf00ab28, cond=0x5612cf00ab50) at ../../../../../include/c11/threads_posix.h:154
#2  0x00007fa04a7fc2fa in radeon_drm_cs_emit_ioctl (sema=0x5612cf00ab28) at ../../../../../src/gallium/auxiliary/os/os_thread.h:259
#3  0x00007fa04a7fc2fa in radeon_drm_cs_emit_ioctl (param=param@entry=0x5612cf00a7e0) at radeon_drm_winsys.c:644
#4  0x00007fa04a7fba37 in impl_thrd_routine (p=<optimized out>) at ../../../../../include/c11/threads_posix.h:87
#5  0x00007fa06aef960a in start_thread (arg=0x7fa046f47700) at pthread_create.c:334
#6  0x00007fa06cd40a9d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7fa074459900 (LWP 29659)):
[KCrash Handler]
#5  0x00007fa057b20f08 in QXcbWindow::setParent(QPlatformWindow const*) (this=0x5612cf3c5840, parent=0x0) at qxcbwindow.cpp:1499
#6  0x00007fa06e9be8bb in QWindow::setParent(QWindow*) (this=0x5612cf3d7340, parent=parent@entry=0x5612cf3bb790) at kernel/qwindow.cpp:614
#7  0x00007fa06f1995d5 in QWidgetPrivate::setParent_sys(QWidget*, QFlags<Qt::WindowType>) (this=this@entry=0x5612cf65f2b0, newparent=newparent@entry=0x5612cf8269c0, f=...) at kernel/qwidget.cpp:10543
#8  0x00007fa06f1a4fda in QWidget::setParent(QWidget*, QFlags<Qt::WindowType>) (this=this@entry=0x5612cf335ab0, parent=parent@entry=0x5612cf8269c0, f=...) at kernel/qwidget.cpp:10398
#9  0x00007fa06f1a60cc in QWidget::setParent(QWidget*) (this=this@entry=0x5612cf335ab0, parent=parent@entry=0x5612cf8269c0) at kernel/qwidget.cpp:10334
#10 0x00007fa06f28c11c in QDialogButtonBox::addButton(QAbstractButton*, QDialogButtonBox::ButtonRole) (this=0x5612cf8269c0, button=0x5612cf335ab0, role=QDialogButtonBox::AcceptRole) at widgets/qdialogbuttonbox.cpp:761
#11 0x00007fa05430cde9 in KDEPlatformFileDialog::KDEPlatformFileDialog() () at /usr/lib64/qt5/plugins/platformthemes/KDEPlatformTheme.so
#12 0x00007fa05430d212 in KDEPlatformFileDialogHelper::KDEPlatformFileDialogHelper() () at /usr/lib64/qt5/plugins/platformthemes/KDEPlatformTheme.so
#13 0x00007fa05430035a in KdePlatformTheme::createPlatformDialogHelper(QPlatformTheme::DialogType) const () at /usr/lib64/qt5/plugins/platformthemes/KDEPlatformTheme.so
#14 0x00007fa06f35b1b5 in QDialogPrivate::platformHelper() const (this=this@entry=0x5612cf6596e0) at dialogs/qdialog.cpp:94
#15 0x00007fa06f36e958 in QFileDialogPrivate::init(QUrl const&, QString const&, QString const&) (this=0x5612cf6596e0) at dialogs/qfiledialog_p.h:112
#16 0x00007fa06f36e958 in QFileDialogPrivate::init(QUrl const&, QString const&, QString const&) (this=0x5612cf6596e0, directory=..., nameFilter=..., caption=...) at dialogs/qfiledialog.cpp:2771
#17 0x00007fa06f36ec76 in QFileDialog::QFileDialog(QFileDialogArgs const&) (this=0x7ffe07428130, args=...) at dialogs/qfiledialog.cpp:379
#18 0x00007fa06f36f22e in QFileDialog::getOpenFileUrls(QWidget*, QString const&, QUrl const&, QString const&, QString*, QFlags<QFileDialog::Option>, QStringList const&) (parent=0x5612ceb3c010, caption=..., dir=..., filter=..., selectedFilter=0x0, options=..., supportedSchemes=...) at dialogs/qfiledialog.cpp:2243
#19 0x00007fa0740e6898 in KateViewManager::slotDocumentOpen() () at /lib64/libkdeinit5_kate.so
#20 0x00007fa0741205f5 in KateViewManager::qt_static_metacall(QObject*, QMetaObject::Call, int, void**) () at /lib64/libkdeinit5_kate.so
#21 0x00007fa06db4d2ea in QMetaObject::activate(QObject*, int, int, void**) (sender=sender@entry=0x5612cec89080, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x7ffe07428460) at kernel/qobject.cpp:3713
#22 0x00007fa06db4dae7 in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) (sender=sender@entry=0x5612cec89080, m=m@entry=0x7fa06f862d40 <QAction::staticMetaObject>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x7ffe07428460) at kernel/qobject.cpp:3578
#23 0x00007fa06f1577d2 in QAction::triggered(bool) (this=this@entry=0x5612cec89080, _t1=false) at .moc/moc_qaction.cpp:365
#24 0x00007fa06f159c58 in QAction::activate(QAction::ActionEvent) (this=0x5612cec89080, event=<optimized out>) at kernel/qaction.cpp:1162
#25 0x00007fa06f25fb80 in QAbstractButtonPrivate::click() (this=0x5612cecf81c0) at widgets/qabstractbutton.cpp:516
#26 0x00007fa06f25fcb4 in QAbstractButton::mouseReleaseEvent(QMouseEvent*) (this=0x5612cecf7f00, e=0x7ffe07428970) at widgets/qabstractbutton.cpp:1132
#27 0x00007fa06f32496a in QToolButton::mouseReleaseEvent(QMouseEvent*) (this=<optimized out>, e=<optimized out>) at widgets/qtoolbutton.cpp:609
#28 0x00007fa06f1a4428 in QWidget::event(QEvent*) (this=0x5612cecf7f00, event=event@entry=0x7ffe07428970) at kernel/qwidget.cpp:9044
#29 0x00007fa06f260a03 in QAbstractButton::event(QEvent*) (this=this@entry=0x5612cecf7f00, e=e@entry=0x7ffe07428970) at widgets/qabstractbutton.cpp:1089
#30 0x00007fa06f324a49 in QToolButton::event(QEvent*) (this=0x5612cecf7f00, event=0x7ffe07428970) at widgets/qtoolbutton.cpp:970
#31 0x00007fa06f16141c in QApplicationPrivate::notify_helper(QObject*, QEvent*) (this=0x5612ce828930, receiver=0x5612cecf7f00, e=0x7ffe07428970) at kernel/qapplication.cpp:3716
#32 0x00007fa06f166fe9 in QApplication::notify(QObject*, QEvent*) (this=<optimized out>, receiver=0x5612cecf7f00, e=0x7ffe07428970) at kernel/qapplication.cpp:3276
#33 0x00007fa06db1e77b in QCoreApplication::notifyInternal(QObject*, QEvent*) (this=0x7ffe074293c0, receiver=0x5612cecf7f00, event=0x7ffe07428970) at kernel/qcoreapplication.cpp:965
#34 0x00007fa06f165ef2 in QApplicationPrivate::sendMouseEvent(QWidget*, QMouseEvent*, QWidget*, QWidget*, QWidget**, QPointer<QWidget>&, bool) (receiver=0x5612cecf7f00, event=0x7ffe07428970, alienWidget=0x5612cecf7f00, nativeWidget=0x5612cecf3c40, buttonDown=<optimized out>, lastMouseReceiver=..., spontaneous=true) at ../../src/corelib/kernel/qcoreapplication.h:227
#35 0x00007fa06f1be98b in QWidgetWindow::handleMouseEvent(QMouseEvent*) (this=this@entry=0x5612cf109bf0, event=event@entry=0x7ffe07428d80) at kernel/qwidgetwindow.cpp:555
#36 0x00007fa06f1c0f4b in QWidgetWindow::event(QEvent*) (this=0x5612cf109bf0, event=0x7ffe07428d80) at kernel/qwidgetwindow.cpp:210
#37 0x00007fa06f16141c in QApplicationPrivate::notify_helper(QObject*, QEvent*) (this=0x5612ce828930, receiver=0x5612cf109bf0, e=0x7ffe07428d80) at kernel/qapplication.cpp:3716
#38 0x00007fa06f1668e6 in QApplication::notify(QObject*, QEvent*) (this=0x7ffe074293c0, receiver=0x5612cf109bf0, e=0x7ffe07428d80) at kernel/qapplication.cpp:3499
#39 0x00007fa06db1e77b in QCoreApplication::notifyInternal(QObject*, QEvent*) (this=0x7ffe074293c0, receiver=receiver@entry=0x5612cf109bf0, event=event@entry=0x7ffe07428d80) at kernel/qcoreapplication.cpp:965
#40 0x00007fa06e9b7ee1 in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) (event=0x7ffe07428d80, receiver=0x5612cf109bf0) at ../../src/corelib/kernel/qcoreapplication.h:227
#41 0x00007fa06e9b7ee1 in QGuiApplicationPrivate::processMouseEvent(QWindowSystemInterfacePrivate::MouseEvent*) (e=0x5612ceeff640) at kernel/qguiapplication.cpp:1789
#42 0x00007fa06e9b9bb5 in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) (e=e@entry=0x5612ceeff640) at kernel/qguiapplication.cpp:1581
#43 0x00007fa06e99d958 in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) (flags=...) at kernel/qwindowsysteminterface.cpp:625
#44 0x00007fa057b3b0a0 in userEventSourceDispatch(GSource*, GSourceFunc, gpointer) (source=<optimized out>) at eventdispatchers/qeventdispatcher_glib.cpp:70
#45 0x00007fa0690e9e3a in g_main_context_dispatch (context=0x7fa0500016f0) at gmain.c:3154
#46 0x00007fa0690e9e3a in g_main_context_dispatch (context=context@entry=0x7fa0500016f0) at gmain.c:3769
#47 0x00007fa0690ea1d0 in g_main_context_iterate (context=context@entry=0x7fa0500016f0, block=block@entry=1, dispatch=dispatch@entry=1, self=<optimized out>) at gmain.c:3840
#48 0x00007fa0690ea27c in g_main_context_iteration (context=0x7fa0500016f0, may_block=may_block@entry=1) at gmain.c:3901
#49 0x00007fa06db74eef in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) (this=0x5612ce889840, flags=...) at kernel/qeventdispatcher_glib.cpp:418
#50 0x00007fa06db1bf0a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) (this=this@entry=0x7ffe07429100, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#51 0x00007fa06db23fec in QCoreApplication::exec() () at kernel/qcoreapplication.cpp:1229
#52 0x00007fa074119834 in kdemain () at /lib64/libkdeinit5_kate.so
#53 0x00007fa06cc5e580 in __libc_start_main (main=0x5612cd89cb10 <main>, argc=1, argv=0x7ffe07429578, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffe07429568) at libc-start.c:289
#54 0x00005612cd89cb49 in _start ()

*** This bug has been marked as a duplicate of bug 356840 ***