SUMMARY
Crash when diffing lots of binary files (PNGs) and scrolling up in the directory view even though its already at the top.

I diffed the files just to see which files changed, not for changes in the files. Had no problems like this before doing similar operations.

STEPS TO REPRODUCE
1. diff two folders containing lots of PNG images (directly and in sub folders)
2. scroll up

OBSERVED RESULT
crash

EXPECTED RESULT
nothing

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Fedora 31 x86_64
(available in About System)
KDE Plasma Version: 5.17.5 (plasmashell --version)
KDE Frameworks Version: 5.66.0
Qt Version: 5.13.2
KDiff3: 1.8.1

ADDITIONAL INFORMATION

Application: KDiff3 (kdiff3), signal: Segmentation fault
Using host libthread_db library "/lib64/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f51a9ba8c80 (LWP 36310))]

Thread 3 (Thread 0x7f518a28d700 (LWP 36329)):
#0  0x00007f51ad1fa44c in read () from /lib64/libc.so.6
#1  0x00007f51944c4365 in pa_read () from /usr/lib64/pulseaudio/libpulsecommon-13.0.so
#2  0x00007f51945483d6 in pa_mainloop_prepare () from /lib64/libpulse.so.0
#3  0x00007f5194548e74 in pa_mainloop_iterate () from /lib64/libpulse.so.0
#4  0x00007f5194548f30 in pa_mainloop_run () from /lib64/libpulse.so.0
#5  0x00007f51945570dd in thread () from /lib64/libpulse.so.0
#6  0x00007f51944f2b9c in internal_thread_func () from /usr/lib64/pulseaudio/libpulsecommon-13.0.so
#7  0x00007f51ac8cf4e2 in start_thread () from /lib64/libpthread.so.0
#8  0x00007f51ad2096d3 in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x7f5196ef1700 (LWP 36312)):
#0  0x00007f51ad1fa44c in read () from /lib64/libc.so.6
#1  0x00007f51abe5653f in g_wakeup_acknowledge () from /lib64/libglib-2.0.so.0
#2  0x00007f51abe0e357 in g_main_context_check () from /lib64/libglib-2.0.so.0
#3  0x00007f51abe0e7b2 in g_main_context_iterate.isra () from /lib64/libglib-2.0.so.0
#4  0x00007f51abe0e943 in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#5  0x00007f51ad8d6843 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#6  0x00007f51ad8801db in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#7  0x00007f51ad6d0c45 in QThread::exec() () from /lib64/libQt5Core.so.5
#8  0x00007f51acbf3f6a in QDBusConnectionManager::run() () from /lib64/libQt5DBus.so.5
#9  0x00007f51ad6d1d96 in QThreadPrivate::start(void*) () from /lib64/libQt5Core.so.5
#10 0x00007f51ac8cf4e2 in start_thread () from /lib64/libpthread.so.0
#11 0x00007f51ad2096d3 in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x7f51a9ba8c80 (LWP 36310)):
[KCrash Handler]
#6  0x00007f51ae2ee194 in QAbstractSlider::value() const () from /lib64/libQt5Widgets.so.5
#7  0x0000559e94734a11 in KDiff3App::scrollDiffTextWindow(int, int) ()
#8  0x00007f51ae236c7e in QWidget::event(QEvent*) () from /lib64/libQt5Widgets.so.5
#9  0x00007f51ae1f3ab6 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#10 0x00007f51ae1fefb4 in QApplication::notify(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#11 0x00007f51ad8813e8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib64/libQt5Core.so.5
#12 0x00007f51ae236c7e in QWidget::event(QEvent*) () from /lib64/libQt5Widgets.so.5
#13 0x00007f51ae2e5f62 in QFrame::event(QEvent*) () from /lib64/libQt5Widgets.so.5
#14 0x00007f51ae46b562 in QAbstractItemView::viewportEvent(QEvent*) () from /lib64/libQt5Widgets.so.5
#15 0x00007f51ae4dc3ef in QTreeView::viewportEvent(QEvent*) () from /lib64/libQt5Widgets.so.5
#16 0x00007f51ad88122e in QCoreApplicationPrivate::sendThroughObjectEventFilters(QObject*, QEvent*) () from /lib64/libQt5Core.so.5
#17 0x00007f51ae1f3aa5 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#18 0x00007f51ae1fefb4 in QApplication::notify(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#19 0x00007f51ad8813e8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib64/libQt5Core.so.5
#20 0x00007f51ae254483 in QWidgetWindow::handleWheelEvent(QWheelEvent*) () from /lib64/libQt5Widgets.so.5
#21 0x00007f51ae255f31 in QWidgetWindow::event(QEvent*) () from /lib64/libQt5Widgets.so.5
#22 0x00007f51ae1f3ab6 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#23 0x00007f51ae1fd150 in QApplication::notify(QObject*, QEvent*) () from /lib64/libQt5Widgets.so.5
#24 0x00007f51ad8813e8 in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /lib64/libQt5Core.so.5
#25 0x00007f51adc5ae67 in QGuiApplicationPrivate::processWheelEvent(QWindowSystemInterfacePrivate::WheelEvent*) () from /lib64/libQt5Gui.so.5
#26 0x00007f51adc6036e in QGuiApplicationPrivate::processWindowSystemEvent(QWindowSystemInterfacePrivate::WindowSystemEvent*) () from /lib64/libQt5Gui.so.5
#27 0x00007f51adc3c6eb in QWindowSystemInterface::sendWindowSystemEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Gui.so.5
#28 0x00007f519ca5fd5e in xcbSourceDispatch(_GSource*, int (*)(void*), void*) () from /lib64/libQt5XcbQpa.so.5
#29 0x00007f51abe0e510 in g_main_context_dispatch () from /lib64/libglib-2.0.so.0
#30 0x00007f51abe0e8a0 in g_main_context_iterate.isra () from /lib64/libglib-2.0.so.0
#31 0x00007f51abe0e943 in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#32 0x00007f51ad8d6825 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#33 0x00007f51ad8801db in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#34 0x00007f51ad8880b6 in QCoreApplication::exec() () from /lib64/libQt5Core.so.5
#35 0x0000559e94707d66 in main ()
[Inferior 1 (process 36310) detached]