Bug 392658

## Description

When customizing the screen corner actions under system settings, searching for a different settings entry will reliably cause systemsettings to crash.

## Steps to reproduce

1. Navigate to the screen corner settings pane
2. Search for any other settings menu, e.g. "Fonts". Perform a few searches if the first one doesn't result in a crash.
3. Systemsettings will crash

## Stacktrace

Application: systemsettings5 (5.12.4)

Qt Version: 5.9.4
Frameworks Version: 5.44.0
Operating System: Linux 4.15.0-13-generic x86_64
Distribution: Ubuntu Bionic Beaver (development branch)

-- Information about the crash:
<Erklären Sie bitte ganz genau, was Sie machten, als das Programm abstürzte.>

The crash can be reproduced every time.

-- Backtrace:
Application: Systemeinstellungen (systemsettings5), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f828d725c80 (LWP 15453))]

Thread 5 (Thread 0x7f825a803700 (LWP 15459)):
#0  0x00007f8288f68bf9 in __GI___poll (fds=0x7f8254003ce0, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007f8282dcf439 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f8282dcf54c in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f82898b44fb in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#4  0x00007f828985961a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007f828967822a in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007f8286da8a45 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#7  0x00007f828967d16d in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007f8288a386db in start_thread (arg=0x7f825a803700) at pthread_create.c:463
#9  0x00007f8288f7588f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 4 (Thread 0x7f82628d9700 (LWP 15457)):
#0  0x00007f8288f640b4 in __GI___libc_read (fd=13, buf=0x7f82628d8b70, nbytes=16) at ../sysdeps/unix/sysv/linux/read.c:27
#1  0x00007f8282e13960 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f8282dcef27 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f8282dcf3e0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f8282dcf54c in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007f82898b44fb in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007f828985961a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007f828967822a in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007f8286da8a45 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Qml.so.5
#9  0x00007f828967d16d in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#10 0x00007f8288a386db in start_thread (arg=0x7f82628d9700) at pthread_create.c:463
#11 0x00007f8288f7588f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 3 (Thread 0x7f82710a2700 (LWP 15455)):
#0  0x00007f8282dcc349 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007f8282dce8d3 in g_main_context_prepare () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007f8282dcf36b in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007f8282dcf54c in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007f82898b44fb in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007f828985961a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#6  0x00007f828967822a in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007f828b1bed45 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5DBus.so.5
#8  0x00007f828967d16d in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#9  0x00007f8288a386db in start_thread (arg=0x7f82710a2700) at pthread_create.c:463
#10 0x00007f8288f7588f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 2 (Thread 0x7f827a579700 (LWP 15454)):
#0  0x00007f8288f68bf9 in __GI___poll (fds=0x7f827a578ca8, nfds=1, timeout=-1) at ../sysdeps/unix/sysv/linux/poll.c:29
#1  0x00007f8284aaa747 in ?? () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#2  0x00007f8284aac36a in xcb_wait_for_event () from /usr/lib/x86_64-linux-gnu/libxcb.so.1
#3  0x00007f827d3261c9 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#4  0x00007f828967d16d in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#5  0x00007f8288a386db in start_thread (arg=0x7f827a579700) at pthread_create.c:463
#6  0x00007f8288f7588f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95

Thread 1 (Thread 0x7f828d725c80 (LWP 15453)):
[KCrash Handler]
#6  0x00007f82898642b0 in QMetaObject::inherits(QMetaObject const*) const () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#7  0x00007f8289864304 in QMetaObject::cast(QObject const*) const () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#8  0x00007f828a8ba21d in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#9  0x00007f828a8746b6 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#10 0x00007f828985b5c8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#11 0x00007f828729fd15 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#12 0x00007f82872abaca in QQuickItemPrivate::deliverKeyEvent(QKeyEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#13 0x00007f82872abe55 in QQuickItem::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#14 0x00007f828a86b82c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#15 0x00007f828a8730f4 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#16 0x00007f828985b5c8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#17 0x00007f82872be018 in QQuickWindow::sendEvent(QQuickItem*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#18 0x00007f82872be32f in QQuickWindow::keyReleaseEvent(QKeyEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#19 0x00007f828a0bb2b5 in QWindow::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
#20 0x00007f82872c4eb5 in QQuickWindow::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Quick.so.5
#21 0x00007f828a86b82c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#22 0x00007f828a8730f4 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#23 0x00007f828985b5c8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#24 0x00007f828792810c in QQuickWidget::keyReleaseEvent(QKeyEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5QuickWidgets.so.5
#25 0x00007f828a8aa048 in QWidget::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#26 0x00007f82879299eb in QQuickWidget::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5QuickWidgets.so.5
#27 0x00007f828a86b82c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#28 0x00007f828a874632 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#29 0x00007f828985b5c8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#30 0x00007f828a8c77b5 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#31 0x00007f828a86b82c in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#32 0x00007f828a8730f4 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#33 0x00007f828985b5c8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#34 0x00007f828a0abfc0 in QGuiApplicationPrivate::processKeyEvent(QWindowSystemInterfacePrivate::KeyEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
#35 0x00007f828a0b0f15 in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
#36 0x00007f828a08828b in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Gui.so.5
#37 0x00007f827d3890e0 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5XcbQpa.so.5
#38 0x00007f8282dcf287 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#39 0x00007f8282dcf4c0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#40 0x00007f8282dcf54c in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#41 0x00007f82898b44df in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#42 0x00007f828985961a in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#43 0x00007f8289862664 in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#44 0x000055ee879cae44 in ?? ()
#45 0x00007f8288e75b97 in __libc_start_main (main=0x55ee879caa40, argc=1, argv=0x7ffd5a533ca8, init=<optimized out>, fini=<optimized out>, rtld_fini=<optimized out>, stack_end=0x7ffd5a533c98) at ../csu/libc-start.c:310
#46 0x000055ee879caeca in _start ()