on OpenBSD, using 4.18.0, xfwm crashes sometimes when alt-tabbing, and the backtrace points at https://gitlab.xfce.org/xfce/xfwm4/-/blob/master/src/tabwin.c#L998, so maybe a null deref ? ``` (gdb) core xfwm4.core [New process 441345] [New process 573830] [New process 416271] [New process 393628] Core was generated by `xfwm4'. Program terminated with signal SIGSEGV, Segmentation fault. #0 tabwinRemoveClient (tabwin=0xea976b5db40, c=0xea9acf58700) at tabwin.c:998 998 tabwin.c: No such file or directory. [Current thread is 1 (process 441345)] (gdb) bt #0 tabwinRemoveClient (tabwin=0xea976b5db40, c=0xea9acf58700) at tabwin.c:998 #1 0x00000ea71d9d1322 in clientCycleEventFilter (event=0xea971291840, data=0x73655dd23db0) at cycle.c:429 #2 0x00000ea71d9d3ce6 in eventXfwmFilter (gdk_xevent=<optimized out>, gevent=<optimized out>, data=<optimized out>) at event_filter.c:175 #3 0x00000ea9de9e05df in _gdk_x11_display_queue_events () from /usr/local/lib/libgdk-3.so.2201.1 #4 0x00000ea9de980d08 in gdk_display_get_event () from /usr/local/lib/libgdk-3.so.2201.1 #5 0x00000ea9de9e0c78 in gdk_event_source_dispatch () from /usr/local/lib/libgdk-3.so.2201.1 #6 0x00000eaa10e0020d in g_main_context_dispatch_unlocked () from /usr/local/lib/libglib-2.0.so.4201.11 #7 0x00000eaa10e005ec in g_main_context_iterate_unlocked () from /usr/local/lib/libglib-2.0.so.4201.11 #8 0x00000eaa10e009fa in g_main_loop_run () from /usr/local/lib/libglib-2.0.so.4201.11 #9 0x00000ea920da74bb in gtk_main () from /usr/local/lib/libgtk-3.so.2201.0 #10 0x00000ea71d9d0f79 in clientCycle (c=<optimized out>, event=0xea971278420) at cycle.c:536 #11 0x00000ea71d9d4719 in handleKeyPress (display_info=0xea9e8833a00, event=0xea971278420) at events.c:329 #12 handleEvent (display_info=0xea9e8833a00, event=0xea971278420) at events.c:2181 #13 xfwm4_event_filter (event=0xea971278420, data=0xea9e8833a00) at events.c:2302 #14 0x00000ea71d9d3ce6 in eventXfwmFilter (gdk_xevent=<optimized out>, gevent=<optimized out>, data=<optimized out>) at event_filter.c:175 #15 0x00000ea9de9e05df in _gdk_x11_display_queue_events () from /usr/local/lib/libgdk-3.so.2201.1 #16 0x00000ea9de980d08 in gdk_display_get_event () from /usr/local/lib/libgdk-3.so.2201.1 #17 0x00000ea9de9e0c78 in gdk_event_source_dispatch () from /usr/local/lib/libgdk-3.so.2201.1 #18 0x00000eaa10e0020d in g_main_context_dispatch_unlocked () from /usr/local/lib/libglib-2.0.so.4201.11 #19 0x00000eaa10e005ec in g_main_context_iterate_unlocked () from /usr/local/lib/libglib-2.0.so.4201.11 #20 0x00000eaa10e009fa in g_main_loop_run () from /usr/local/lib/libglib-2.0.so.4201.11 #21 0x00000ea920da74bb in gtk_main () from /usr/local/lib/libgtk-3.so.2201.0 #22 0x00000ea71d9e3495 in main (argc=1, argv=0x73655dd24758) at main.c:764 ```