I got similar stacktrace. I just click to akregator icon in kontact and it crashed. I have kdepim compiled from source, my head is dcb4a0d0e469745ddcc050c609fa5995109b7ac8. 

Application: Kontact (kontact), signal: Segmentation fault
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fb873ca9840 (LWP 2616))]

Thread 27 (Thread 0x7fb86af85700 (LWP 2634)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007fb88aec548b in ?? () from /usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
#2  0x00007fb88aec54c9 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
#3  0x00007fb886b6c6aa in start_thread (arg=0x7fb86af85700) at pthread_create.c:333
#4  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 26 (Thread 0x7fb827979700 (LWP 2651)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb8200008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb827978d80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x23ecc50) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb827979700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 25 (Thread 0x7fb8255bb700 (LWP 2690)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007fb88abd35b4 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
#2  0x00007fb88aef5341 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
#3  0x00007fb886b6c6aa in start_thread (arg=0x7fb8255bb700) at pthread_create.c:333
#4  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 24 (Thread 0x7fb824d9b700 (LWP 2691)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007fb88abd45e3 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
#2  0x00007fb88aef5341 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
#3  0x00007fb886b6c6aa in start_thread (arg=0x7fb824d9b700) at pthread_create.c:333
#4  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 23 (Thread 0x7fb81ffff700 (LWP 2692)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007fb88abd45e3 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
#2  0x00007fb88aef5341 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
#3  0x00007fb886b6c6aa in start_thread (arg=0x7fb81ffff700) at pthread_create.c:333
#4  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 22 (Thread 0x7fb81f7fe700 (LWP 2693)):
#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007fb88abd45e3 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
#2  0x00007fb88aef5341 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5WebKit.so.5
#3  0x00007fb886b6c6aa in start_thread (arg=0x7fb81f7fe700) at pthread_create.c:333
#4  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 21 (Thread 0x7fb8052ed700 (LWP 2711)):
#0  0x00007fb88cdd849d in read () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863884e0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb886344cd4 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb886345190 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb8000008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#6  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb8052ecd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#7  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#8  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x2754c00) at thread/qthread_unix.cpp:337
#9  0x00007fb886b6c6aa in start_thread (arg=0x7fb8052ed700) at pthread_create.c:333
#10 0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 20 (Thread 0x7fb804aec700 (LWP 2712)):
#0  0x00007fb88cdd849d in read () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863884e0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb886344cd4 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb886345190 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7f80008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#6  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb804aebd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#7  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#8  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x22e9f20) at thread/qthread_unix.cpp:337
#9  0x00007fb886b6c6aa in start_thread (arg=0x7fb804aec700) at pthread_create.c:333
#10 0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 19 (Thread 0x7fb7fffff700 (LWP 2716)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7f40008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7ffffed80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x276b690) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7fffff700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 18 (Thread 0x7fb7ff7fe700 (LWP 2720)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7ec0008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7ff7fdd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x2c659b0) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7ff7fe700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 17 (Thread 0x7fb7feffd700 (LWP 2724)):
#0  0x00007fb88cdd849d in read () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863884e0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb886344cd4 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb886345190 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7f00008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#6  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7feffcd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#7  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#8  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x28aa3c0) at thread/qthread_unix.cpp:337
#9  0x00007fb886b6c6aa in start_thread (arg=0x7fb7feffd700) at pthread_create.c:333
#10 0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 16 (Thread 0x7fb7fe7fc700 (LWP 2726)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7e40008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7fe7fbd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x2a487e0) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7fe7fc700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 15 (Thread 0x7fb7fcddc700 (LWP 2731)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7e80008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7fcddbd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x28b60d0) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7fcddc700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 14 (Thread 0x7fb7e3fff700 (LWP 2734)):
#0  0x00007fb88cdd849d in read () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863884e0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb886344cd4 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb886345190 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7dc0008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#6  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7e3ffed80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#7  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#8  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x28fd7d0) at thread/qthread_unix.cpp:337
#9  0x00007fb886b6c6aa in start_thread (arg=0x7fb7e3fff700) at pthread_create.c:333
#10 0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 13 (Thread 0x7fb7e37fe700 (LWP 2737)):
#0  0x00007fb886389869 in g_mutex_lock () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007fb8863450f0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7d40008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7e37fdd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x28e18e0) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7e37fe700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 12 (Thread 0x7fb7e23bd700 (LWP 2746)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7d80008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7e23bcd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x2e2bb80) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7e23bd700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 11 (Thread 0x7fb7e1bbc700 (LWP 2749)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7cc0008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7e1bbbd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x2beb040) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7e1bbc700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 10 (Thread 0x7fb7d0897700 (LWP 2787)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7c00008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7d0896d80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x3032ce0) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7d0897700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 9 (Thread 0x7fb7c6c5d700 (LWP 2796)):
#0  0x00007fb886389869 in g_mutex_lock () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007fb8863450f0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7bc0008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7c6c5cd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x3009420) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7c6c5d700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 8 (Thread 0x7fb7d16b6700 (LWP 7909)):
#0  0x00007fb886389869 in g_mutex_lock () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007fb886344180 in g_main_context_acquire () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863450a5 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7c8003500, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#5  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7d16b5d80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#6  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#7  0x00007fb88d6e62be in QThreadPrivate::start (arg=0xb2a1ef0) at thread/qthread_unix.cpp:337
#8  0x00007fb886b6c6aa in start_thread (arg=0x7fb7d16b6700) at pthread_create.c:333
#9  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 7 (Thread 0x7fb7ba724700 (LWP 8010)):
#0  0x00007fb886344c78 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007fb886345190 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7b40008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7ba723d80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0x2cf4350) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7ba724700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 6 (Thread 0x7fb7b9f23700 (LWP 8013)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7ac0008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7b9f22d80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0xbc7d520) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7b9f23700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 5 (Thread 0x7fb7b9722700 (LWP 8016)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7b00008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7b9721d80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0xbc043f0) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7b9722700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 4 (Thread 0x7fb7b8f21700 (LWP 8019)):
#0  0x00007fb88cddc8dd in poll () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863451ec in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7a40008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#4  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7b8f20d80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#5  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#6  0x00007fb88d6e62be in QThreadPrivate::start (arg=0xba13b50) at thread/qthread_unix.cpp:337
#7  0x00007fb886b6c6aa in start_thread (arg=0x7fb7b8f21700) at pthread_create.c:333
#8  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 3 (Thread 0x7fb7abfff700 (LWP 8022)):
#0  0x00007fb88cdd849d in read () at ../sysdeps/unix/syscall-template.S:81
#1  0x00007fb8863884e0 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb886344cd4 in g_main_context_check () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb886345190 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#5  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7a00008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#6  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7abffed80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#7  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#8  0x00007fb88d6e62be in QThreadPrivate::start (arg=0xb4ee700) at thread/qthread_unix.cpp:337
#9  0x00007fb886b6c6aa in start_thread (arg=0x7fb7abfff700) at pthread_create.c:333
#10 0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 2 (Thread 0x7fb7ab7fe700 (LWP 8025)):
#0  0x00007fb886389884 in g_mutex_unlock () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#1  0x00007fb8863441ee in g_main_context_acquire () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#2  0x00007fb8863450a5 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#3  0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#4  0x00007fb88d91d29b in QEventDispatcherGlib::processEvents (this=0x7fb7980008c0, flags=...) at kernel/qeventdispatcher_glib.cpp:420
#5  0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7fb7ab7fdd80, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#6  0x00007fb88d6e13d4 in QThread::exec (this=<optimized out>) at thread/qthread.cpp:503
#7  0x00007fb88d6e62be in QThreadPrivate::start (arg=0xb9bef60) at thread/qthread_unix.cpp:337
#8  0x00007fb886b6c6aa in start_thread (arg=0x7fb7ab7fe700) at pthread_create.c:333
#9  0x00007fb88cde7eed in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109

Thread 1 (Thread 0x7fb873ca9840 (LWP 2616)):
[KCrash Handler]
#6  0x00007fb87394002c in QXcbWindow::devicePixelRatio (this=<optimized out>) at qxcbwindow.cpp:2457
#7  0x00007fb873942244 in QXcbWindow::propagateSizeHints (this=0x2ed7a80) at qxcbwindow.cpp:1496
#8  0x00007fb87394636c in QXcbWindow::setGeometry (this=0x2ed7a80, rect=...) at qxcbwindow.cpp:603
#9  0x00007fb88e418302 in QWidgetPrivate::show_sys (this=this@entry=0x2eee2e0) at kernel/qwidget.cpp:7865
#10 0x00007fb88e42168e in QWidgetPrivate::show_helper (this=this@entry=0x2eee2e0) at kernel/qwidget.cpp:7803
#11 0x00007fb88e423815 in QWidget::setVisible (this=0x2eee200, visible=<optimized out>) at kernel/qwidget.cpp:8087
#12 0x00007fb88e406dd9 in QStackedLayout::setCurrentIndex (this=0x2391f60, index=2) at kernel/qstackedlayout.cpp:324
#13 0x00007fb88e406fc4 in QStackedLayout::setCurrentWidget (this=0x2391f60, widget=widget@entry=0x2eee200) at kernel/qstackedlayout.cpp:379
#14 0x00007fb88e57a4b1 in QStackedWidget::setCurrentWidget (this=<optimized out>, widget=0x2eee200) at widgets/qstackedwidget.cpp:242
#15 0x00007fb88f640f16 in Kontact::MainWindow::selectPlugin (this=0x239a680, plugin=0x26f7c50) at /var/btrfs/@src/kdepim/kontact/src/mainwindow.cpp:843
#16 0x00007fb88f65cd9b in Kontact::MainWindow::qt_static_metacall (_o=0x239a680, _c=QMetaObject::InvokeMetaMethod, _id=0, _a=0x7ffd442031a0) at /var/btrfs/@src/kdepim/myBuild/kontact/src/moc_mainwindow.cpp:150
#17 0x00007fb88d8f678a in QMetaObject::activate (sender=0x23c67f0, signalOffset=<optimized out>, local_signal_index=<optimized out>, argv=<optimized out>) at kernel/qobject.cpp:3717
#18 0x00007fb88f65d334 in Kontact::SidePaneBase::pluginSelected (this=0x23c67f0, _t1=0x26f7c50) at /var/btrfs/@src/kdepim/myBuild/kontact/src/moc_sidepanebase.cpp:133
#19 0x00007fb88f655989 in QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<KontactInterface::Plugin*>, void, void (Kontact::SidePaneBase::*)(KontactInterface::Plugin*)>::call (f=(void (Kontact::SidePaneBase::*)(Kontact::SidePaneBase * const, KontactInterface::Plugin *)) 0x7fb88f65d2de <Kontact::SidePaneBase::pluginSelected(KontactInterface::Plugin*)>, o=0x23c67f0, arg=0x7ffd442033a0) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:500
#20 0x00007fb88f655747 in QtPrivate::FunctionPointer<void (Kontact::SidePaneBase::*)(KontactInterface::Plugin*)>::call<QtPrivate::List<KontactInterface::Plugin*>, void> (f=(void (Kontact::SidePaneBase::*)(Kontact::SidePaneBase * const, KontactInterface::Plugin *)) 0x7fb88f65d2de <Kontact::SidePaneBase::pluginSelected(KontactInterface::Plugin*)>, o=0x23c67f0, arg=0x7ffd442033a0) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:519
#21 0x00007fb88f65554b in QtPrivate::QSlotObject<void (Kontact::SidePaneBase::*)(KontactInterface::Plugin*), QtPrivate::List<KontactInterface::Plugin*>, void>::impl (which=1, this_=0x23bb6d0, r=0x23c67f0, a=0x7ffd442033a0, ret=0x0) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobject_impl.h:143
#22 0x00007fb88d8f6617 in QtPrivate::QSlotObjectBase::call (a=0x7ffd442033a0, r=0x23c67f0, this=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qobject_impl.h:124
#23 QMetaObject::activate (sender=0x23bee50, signalOffset=<optimized out>, local_signal_index=<optimized out>, argv=<optimized out>) at kernel/qobject.cpp:3702
#24 0x00007fb88f65ca02 in Kontact::Navigator::pluginActivated (this=0x23bee50, _t1=0x26f7c50) at /var/btrfs/@src/kdepim/myBuild/kontact/src/moc_iconsidepane.cpp:147
#25 0x00007fb88f652a37 in Kontact::Navigator::slotCurrentChanged (this=0x23bee50, current=...) at /var/btrfs/@src/kdepim/kontact/src/iconsidepane.cpp:492
#26 0x00007fb88f65588c in QtPrivate::FunctorCall<QtPrivate::IndexesList<0>, QtPrivate::List<QModelIndex const&>, void, void (Kontact::Navigator::*)(QModelIndex const&)>::call (f=(void (Kontact::Navigator::*)(Kontact::Navigator * const, const QModelIndex &)) 0x7fb88f652936 <Kontact::Navigator::slotCurrentChanged(QModelIndex const&)>, o=0x23bee50, arg=0x7ffd44203600) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:500
#27 0x00007fb88f655626 in QtPrivate::FunctionPointer<void (Kontact::Navigator::*)(QModelIndex const&)>::call<QtPrivate::List<QModelIndex const&>, void> (f=(void (Kontact::Navigator::*)(Kontact::Navigator * const, const QModelIndex &)) 0x7fb88f652936 <Kontact::Navigator::slotCurrentChanged(QModelIndex const&)>, o=0x23bee50, arg=0x7ffd44203600) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobjectdefs_impl.h:519
#28 0x00007fb88f655323 in QtPrivate::QSlotObject<void (Kontact::Navigator::*)(QModelIndex const&), QtPrivate::List<QModelIndex const&>, void>::impl (which=1, this_=0x23c7040, r=0x23bee50, a=0x7ffd44203600, ret=0x0) at /usr/include/x86_64-linux-gnu/qt5/QtCore/qobject_impl.h:143
#29 0x00007fb88d8f6617 in QtPrivate::QSlotObjectBase::call (a=0x7ffd44203600, r=0x23bee50, this=<optimized out>) at ../../include/QtCore/../../src/corelib/kernel/qobject_impl.h:124
#30 QMetaObject::activate (sender=sender@entry=0x23c4c40, signalOffset=<optimized out>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x7ffd44203600) at kernel/qobject.cpp:3702
#31 0x00007fb88d8f6f87 in QMetaObject::activate (sender=sender@entry=0x23c4c40, m=m@entry=0x7fb88daf6120 <QItemSelectionModel::staticMetaObject>, local_signal_index=local_signal_index@entry=1, argv=argv@entry=0x7ffd44203600) at kernel/qobject.cpp:3582
#32 0x00007fb88d8772aa in QItemSelectionModel::currentChanged (this=this@entry=0x23c4c40, _t1=..., _t2=...) at .moc/moc_qitemselectionmodel.cpp:287
#33 0x00007fb88d87750d in QItemSelectionModel::setCurrentIndex (this=this@entry=0x23c4c40, index=..., command=command@entry=...) at itemmodels/qitemselectionmodel.cpp:1324
#34 0x00007fb88e63a78c in QAbstractItemView::mousePressEvent (this=0x23bee50, event=<optimized out>) at itemviews/qabstractitemview.cpp:1727
#35 0x00007fb88e4245cf in QWidget::event (this=this@entry=0x23bee50, event=event@entry=0x7ffd44203da0) at kernel/qwidget.cpp:8653
#36 0x00007fb88e51e76e in QFrame::event (this=0x23bee50, e=0x7ffd44203da0) at widgets/qframe.cpp:526
#37 0x00007fb88e641a4b in QAbstractItemView::viewportEvent (this=0x23bee50, event=0x7ffd44203da0) at itemviews/qabstractitemview.cpp:1689
#38 0x00007fb88d8c5d0c in QCoreApplicationPrivate::sendThroughObjectEventFilters (this=this@entry=0x22b5bc0, receiver=receiver@entry=0x23ba790, event=event@entry=0x7ffd44203da0) at kernel/qcoreapplication.cpp:1031
#39 0x00007fb88e3e1b6c in QApplicationPrivate::notify_helper (this=this@entry=0x22b5bc0, receiver=receiver@entry=0x23ba790, e=e@entry=0x7ffd44203da0) at kernel/qapplication.cpp:3716
#40 0x00007fb88e3e7c7a in QApplication::notify (this=<optimized out>, receiver=0x23ba790, e=0x7ffd44203da0) at kernel/qapplication.cpp:3280
#41 0x00007fb88d8c5f1b in QCoreApplication::notifyInternal (this=0x7ffd44204790, receiver=receiver@entry=0x23ba790, event=event@entry=0x7ffd44203da0) at kernel/qcoreapplication.cpp:935
#42 0x00007fb88e3e66f2 in QCoreApplication::sendSpontaneousEvent (event=0x7ffd44203da0, receiver=0x23ba790) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#43 QApplicationPrivate::sendMouseEvent (receiver=receiver@entry=0x23ba790, event=event@entry=0x7ffd44203da0, alienWidget=alienWidget@entry=0x23ba790, nativeWidget=0x23c67f0, buttonDown=buttonDown@entry=0x7fb88e907a10 <qt_button_down>, lastMouseReceiver=..., spontaneous=true) at kernel/qapplication.cpp:2751
#44 0x00007fb88e43b440 in QWidgetWindow::handleMouseEvent (this=this@entry=0x2e40db0, event=event@entry=0x7ffd442041c0) at kernel/qwidgetwindow.cpp:543
#45 0x00007fb88e43d78b in QWidgetWindow::event (this=0x2e40db0, event=0x7ffd442041c0) at kernel/qwidgetwindow.cpp:210
#46 0x00007fb88e3e1b8c in QApplicationPrivate::notify_helper (this=this@entry=0x22b5bc0, receiver=receiver@entry=0x2e40db0, e=e@entry=0x7ffd442041c0) at kernel/qapplication.cpp:3720
#47 0x00007fb88e3e7230 in QApplication::notify (this=0x7ffd44204790, receiver=0x2e40db0, e=0x7ffd442041c0) at kernel/qapplication.cpp:3503
#48 0x00007fb88d8c5f1b in QCoreApplication::notifyInternal (this=0x7ffd44204790, receiver=receiver@entry=0x2e40db0, event=event@entry=0x7ffd442041c0) at kernel/qcoreapplication.cpp:935
#49 0x00007fb88dbe83c8 in QCoreApplication::sendSpontaneousEvent (event=0x7ffd442041c0, receiver=0x2e40db0) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#50 QGuiApplicationPrivate::processMouseEvent (e=0x88d4910) at kernel/qguiapplication.cpp:1772
#51 0x00007fb88dbea005 in QGuiApplicationPrivate::processWindowSystemEvent (e=e@entry=0x88d4910) at kernel/qguiapplication.cpp:1576
#52 0x00007fb88dbcf5b8 in QWindowSystemInterface::sendWindowSystemEvents (flags=...) at kernel/qwindowsysteminterface.cpp:572
#53 0x00007fb87395c250 in userEventSourceDispatch (source=<optimized out>) at eventdispatchers/qeventdispatcher_glib.cpp:70
#54 0x00007fb886344ff7 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#55 0x00007fb886345250 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#56 0x00007fb8863452fc in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#57 0x00007fb88d91d27f in QEventDispatcherGlib::processEvents (this=0x22f2980, flags=...) at kernel/qeventdispatcher_glib.cpp:418
#58 0x00007fb88d8c375a in QEventLoop::exec (this=this@entry=0x7ffd44204540, flags=..., flags@entry=...) at kernel/qeventloop.cpp:204
#59 0x00007fb88d8cb2cc in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1188
#60 0x0000000000408992 in main (argc=1, argv=0x7ffd442048c8) at /var/btrfs/@src/kdepim/kontact/src/main.cpp:221

This bug has never been confirmed for a Kontact version that is based on KDE Frameworks, except possibly a Technology Preview version 5.0.x. Those versions differ significantly from the old 4.x series. Therefore, I plan to close it in around two or three months. In the meantime, it is set to WAITINGFORINFO to give reporters the opportunity to check if it is still valid. As soon as someone confirms it for a recent version (at least 5.1, ideally even more recent), I'll gladly reopen it.

Please understand that we lack the manpower to triage bugs reported for versions almost two years beyond their end of life.

Just as announced in my last comment, I close this bug. If you encounter it again in a recent version (at least 5.1 aka 15.12; preferably much more recent), please open a new one unless it already exists. Thank you for all your input.