Application: kwin_x11 (5.3.90)
 (Compiled from sources)
Qt Version: 5.4.1
Operating System: Linux 4.0.2-1-ARCH x86_64
Distribution: "Arch Linux"

-- Information about the crash:
- What I was doing when the application crashed:

Attempt to fix kwin bugs not going to kwin component

Steps

1) open konsole
2) start kwin

The crash can be reproduced sometimes.

-- Backtrace:
Application: KWin (kwin_x11), signal: Segmentation fault
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[Current thread is 1 (Thread 0x7f723fe38800 (LWP 8420))]

Thread 2 (Thread 0x7f72263b0700 (LWP 8421)):
#0  0x00007f723f7f4e8d in poll () from /usr/lib/libc.so.6
#1  0x00007f723cfd99f2 in ?? () from /usr/lib/libxcb.so.1
#2  0x00007f723cfdb56f in xcb_wait_for_event () from /usr/lib/libxcb.so.1
#3  0x00007f7226e52619 in ?? () from /usr/lib/qt/plugins/platforms/libqxcb.so
#4  0x00007f723d29218e in ?? () from /usr/lib/libQt5Core.so.5
#5  0x00007f723ef75354 in start_thread () from /usr/lib/libpthread.so.0
#6  0x00007f723f7fdbfd in clone () from /usr/lib/libc.so.6

Thread 1 (Thread 0x7f723fe38800 (LWP 8420)):
[KCrash Handler]
#6  kdemain (argc=2, argv=0x7fffa0b28558) at /home/bshah/aur/kwin-git/src/kwin/main_x11.cpp:273
#7  0x00000000004008e2 in main (argc=2, argv=0x7fffa0b28558) at /home/bshah/aur/kwin-git/src/build/kwin_x11_dummy.cpp:3

Reported using DrKonqi