can't find 'e/shelf/base/default' in default elementary theme. What version are you using?

Of course "e/shelf/default/base"
My mistake.

Hm.. I can't reproduce your segfault, but after 2-4 copies of that group i'm getting another one on cahsh_flush:

Program received signal SIGSEGV, Segmentation fault.
_edje_collection_free_part_description_clean (type=1, desc=0x2438810, free_strings=<optimized out>) at lib/edje/edje_load.c:2007
(gdb) bt
#0 _edje_collection_free_part_description_clean (type=1, desc=0x2438810, free_strings=<optimized out>) at lib/edje/edje_load.c:2007
#1 0x00007ffff60aa7c7 in _edje_collection_free (edf=edf@entry=0x1a177a0, ec=ec@entry=0x1ef1420, ce=0x243b6d0) at lib/edje/edje_load.c:1937
#2 0x00007ffff604b9c4 in _edje_cache_coll_flush (edf=edf@entry=0x1a177a0) at lib/edje/edje_cache.c:551
#3 0x00007ffff60a754c in _edje_file_free (edf=0x1a177a0) at lib/edje/edje_load.c:1755
#4 0x00007ffff6049eee in _edje_cache_file_clean () at lib/edje/edje_cache.c:600
#5 0x00007ffff604bbb6 in edje_file_cache_flush () at lib/edje/edje_cache.c:662
#6 0x00007ffff7849c2b in elm_cache_all_flush () at elm_main.c:1334
#7 0x00007ffff77afa19 in _elm_cache_flush_cb (data=<optimized out>) at elm_config.c:1584
#8 0x00007ffff695c375 in _ecore_poller_cb_timer (data=<optimized out>) at lib/ecore/ecore_poller.c:148
#9 0x00007ffff695e730 in _ecore_call_task_cb (data=<optimized out>, func=<optimized out>) at lib/ecore/ecore_private.h:282
#10 _ecore_timer_expired_call (when=178529,97901310099) at lib/ecore/ecore_timer.c:692
#11 0x00007ffff695e8eb in _ecore_timer_expired_timers_call (when=178529,97901310099) at lib/ecore/ecore_timer.c:646
#12 0x00007ffff695a5e5 in _ecore_main_loop_iterate_internal (once_only=1) at lib/ecore/ecore_main.c:2226
#13 0x00007ffff695ab57 in ecore_main_loop_iterate_may_block (may_block=may_block@entry=0) at lib/ecore/ecore_main.c:1250
#14 0x0000000000416c07 in eflete_main_loop_begin () at ../../src/bin/eflete.c:59
#15 0x000000000041ed26 in popup_want_action (title=0x4a25ff "Create a new layout", msg=msg@entry=0x0, content=content@entry=0x400002a1400130f2, to_focus=to_focus@entry=0x400002a3a00130fb, popup_btns=popup_btns@entry=(BTN_OK | BTN_C
ANCEL), func=func@entry=0x0, data=0x400002a3a00130fb) at ../../src/bin/ui/popup.c:132
#16 0x0000000000422123 in _btn_add_group_cb (data=<optimized out>, obj=<optimized out>, event_info=<optimized out>) at ../../src/bin/ui/project_navigator.c:469
#17 0x00007ffff6c0a1ca in _eo_evas_smart_cb (data=<optimized out>, event=<optimized out>) at lib/evas/canvas/evas_object_smart.c:67
#18 0x00007ffff5e15e65 in _eo_base_event_callback_call (obj_id=<optimized out>, pd=0x9bc500, desc=0x7ffff6f95680 <_EVAS_CLICKABLE_INTERFACE_EVENT_CLICKED>, event_info=<optimized out>) at lib/eo/eo_base_class.c:715
#19 0x00007ffff5e14c5b in eo_event_callback_call (obj=0x40000009d000009e, desc=0x7ffff6f95680 <_EVAS_CLICKABLE_INTERFACE_EVENT_CLICKED>, event_info=0x0) at lib/eo/eo_base.eo.c:94
#20 0x00007ffff60b22fb in edje_match_callback_exec_check_finals (prop=<optimized out>, ed=<optimized out>, source=0x7ffff7483afe "", sig=0x9b2ffc "elm,action,click", source_states=<optimized out>, signal_states=<optimized out>, mat
ches=<optimized out>, ssp=0xa208d0) at lib/edje/edje_match.c:556
#21 edje_match_callback_exec (ssp=0xa208d0, matches=<optimized out>, sig=0x9b2ffc "elm,action,click", source=0x7ffff7483afe "", ed=<optimized out>, prop=0 '\000') at lib/edje/edje_match.c:711
#22 0x00007ffff60b86d9 in _edje_emit_cb (prop=<optimized out>, data=<optimized out>, src=<optimized out>, sig=<optimized out>, ed=<optimized out>) at lib/edje/edje_program.c:1461
#23 _edje_emit_handle (ed=0x9bcbc0, sig=0x9b2ffc "elm,action,click", src=0x7ffff7483afe "", sdata=0x9, prop=0 '\000') at lib/edje/edje_program.c:1413
#24 0x00007ffff60b367f in _edje_message_queue_process () at lib/edje/edje_message_queue.c:787
#25 0x00007ffff60b3827 in _edje_job (data=<optimized out>) at lib/edje/edje_message_queue.c:154
#26 0x00007ffff6957d8b in _ecore_job_event_handler (data=<optimized out>, type=<optimized out>, ev=<optimized out>) at lib/ecore/ecore_job.c:121
#27 0x00007ffff6952516 in _ecore_call_handler_cb (event=<optimized out>, type=<optimized out>, data=<optimized out>, func=<optimized out>) at lib/ecore/ecore_private.h:316
#28 _ecore_event_call () at lib/ecore/ecore_events.c:518
#29 0x00007ffff695a880 in _ecore_main_loop_iterate_internal (once_only=0) at lib/ecore/ecore_main.c:2339
#30 0x00007ffff695ac27 in ecore_main_loop_begin () at lib/ecore/ecore_main.c:1284
#31 0x0000000000416ac9 in elm_main (argc=0, argv=0x7fffffffdd78) at ../../src/bin/main.c:185
#32 0x00000000004166cc in main (argc=1, argv=0x7fffffffdd78) at ../../src/bin/main.c:194

Oh, yes. I have this crash too, some days ago but it really depends from edje cache flushing mechanism. We also should think about this. Actually after disabling flush edje collections - this crash going a rare. I think you should create another ticket in 3rd party/pending column with High priority, And we can discuss about possible way to solve it in relative ticket.

But I still receive segfault that reported in this ticket. But it happens randomly. I hate the random.

I spent an hour trying to reproduce this crash, but Eflete still working.

My configuration
Render: OpenGL
Cache Flush interval: 512 ticks
Font Cache Size: 0.5MB
Image Cache Size: 4 MB
Edje Files to Cache: 32
Edje Collection to Cache: 64

Anyway, in case if some one will have steps to reproduce this issue please notify. Right now i move this ticket to the 3rd party/pending column with the same priority.

Testification for testing genlist

Things I found could make better but.... I am not sure since they are dated by 2015 year. So I am not sure absolutely:

I think I need poke upstream people, should I?