as per the title, on up to date Archlinux Plasma (KDE 5, X11)
new search window appears momentarily or the app just chashes (disappears) immediately on content menu click:

(gdb) start
warning: Unexpected size of section `.reg-xstate/211812' in core file.
Function "main" not defined.
Make breakpoint pending on future shared library load? (y or [n]) y
Temporary breakpoint 1 (-qualified main if $_inferior == 1) pending.
Starting program: /usr/bin/darkmx
[Thread debugging using libthread_db enabled]                                                                                              
Using host libthread_db library "/usr/lib/libthread_db.so.1".
[New Thread 0x7ffff2fff6c0 (LWP 214509)]                                                                                                    
[New Thread 0x7ffff27fe6c0 (LWP 214510)]                                                                                                    
[Thread 0x7ffff27fe6c0 (LWP 214510) exited]
[New Thread 0x7ffff27fe6c0 (LWP 214511)]
[New Thread 0x7ffff1d226c0 (LWP 214512)]
[Thread 0x7ffff27fe6c0 (LWP 214511) exited]
[Thread 0x7ffff1d226c0 (LWP 214512) exited]
[New Thread 0x7ffff1d226c0 (LWP 214521)]
[New Thread 0x7ffff27fe6c0 (LWP 214522)]
[New Thread 0x7ffff15216c0 (LWP 214524)]
[Thread 0x7ffff15216c0 (LWP 214524) exited]
[New Thread 0x7ffff15216c0 (LWP 214525)]
[Thread 0x7ffff15216c0 (LWP 214525) exited]
[New Thread 0x7ffff15216c0 (LWP 214526)]
[New Thread 0x7ffff086b6c0 (LWP 214530)]                                                                                                    
[New Thread 0x7fffeb70d6c0 (LWP 214531)]                                                                                                    
[Thread 0x7fffeb70d6c0 (LWP 214531) exited]
[New Thread 0x7fffeb70d6c0 (LWP 214532)]
[New Thread 0x7fffeaf0c6c0 (LWP 214533)]
[New Thread 0x7fffea70b6c0 (LWP 214534)]
[Thread 0x7fffeaf0c6c0 (LWP 214533) exited]
[Thread 0x7fffeb70d6c0 (LWP 214532) exited]
[Thread 0x7fffea70b6c0 (LWP 214534) exited]
[New Thread 0x7fffea70b6c0 (LWP 214535)]
[Thread 0x7fffea70b6c0 (LWP 214535) exited]
[New Thread 0x7fffea70b6c0 (LWP 214536)]
[New Thread 0x7fffeb70d6c0 (LWP 214537)]
[Thread 0x7fffeb70d6c0 (LWP 214537) exited]
[New Thread 0x7fffeb70d6c0 (LWP 214538)]
[Thread 0x7fffea70b6c0 (LWP 214536) exited]
[Thread 0x7fffeb70d6c0 (LWP 214538) exited]
[New Thread 0x7fffeb70d6c0 (LWP 214539)]
[New Thread 0x7fffea70b6c0 (LWP 214540)]
[Thread 0x7fffeb70d6c0 (LWP 214539) exited]
[Thread 0x7fffea70b6c0 (LWP 214540) exited]
[New Thread 0x7fffea70b6c0 (LWP 214541)]
[Thread 0x7fffea70b6c0 (LWP 214541) exited]
[New Thread 0x7fffea70b6c0 (LWP 214542)]
[New Thread 0x7fffeb70d6c0 (LWP 214543)]
[Thread 0x7fffea70b6c0 (LWP 214542) exited]
[New Thread 0x7fffea70b6c0 (LWP 214544)]
[Thread 0x7fffeb70d6c0 (LWP 214543) exited]
[Thread 0x7fffea70b6c0 (LWP 214544) exited]
[New Thread 0x7fffea70b6c0 (LWP 214550)]
[New Thread 0x7fffeb70d6c0 (LWP 214551)]
[New Thread 0x7fffeaf0c6c0 (LWP 214552)]
[New Thread 0x7fffcbfff6c0 (LWP 214553)]
[New Thread 0x7fffcb7fe6c0 (LWP 214554)]
[Detaching after fork from child process 214555]
[New Thread 0x7fffcaffd6c0 (LWP 214590)]
[New Thread 0x7fffca7fc6c0 (LWP 214598)]
[New Thread 0x7fffc9ffb6c0 (LWP 214599)]
[New Thread 0x7fffc97fa6c0 (LWP 214600)]
[Thread 0x7ffff15216c0 (LWP 214526) exited]
[Detaching after fork from child process 214694]
Downloading separate debug info for /usr/lib/gdk-pixbuf-2.0/2.10.0/loaders/libpixbufloader-svg.so
Downloading separate debug info for /usr/lib/librsvg-2.so.2                                                                                
                                                                                                                                           
Thread 1 "darkmx" received signal SIGSEGV, Segmentation fault.
0x00000000016b7d67 in ?? ()
(gdb) exit
A debugging session is active.

       Inferior 1 [process 214495] will be killed.

Quit anyway? (y or n) y


Thanks for reporting this.
It will be fixed in the next release.

v1.31, not sure which's the next, still crash but now writes darkmx_crash_report.dat on desktop without asking...

(Log removed by Mod and sent to Devs)