I got the following trace. ES did not crash for me. Since the compilation was not successful when this trace was recorded in the Class tool, this could be an expected behavior if it didn't crash your ES either. index_small_enough: Assertion violated. (CHECK_VIOLATION) ******************************** Thread exception ***************************** In thread Root thread 0x0 (thread id) ******************************************************************************* ------------------------------------------------------------------------------- Class / Object Routine Nature of exception Effect ------------------------------------------------------------------------------- FIXED_LIST item @3 index_small_enough: <000000000EA71800> Runtime check violated. Fail ------------------------------------------------------------------------------- FIXED_LIST item @3 <000000000EA71800> Routine failure. Fail ------------------------------------------------------------------------------- QL_FEATURE_DOMAIN_GENERATOR record_ancestors_of_class @6 <000000000EE57BAC> (From QL_DOMAIN_GENERATOR) Routine failure. Fail ------------------------------------------------------------------------------- QL_FEATURE_DOMAIN_GENERATOR process_feature_from_class @16 <000000000EE57BAC> (From QL_DOMAIN_GENERATOR) Routine failure. Fail ------------------------------------------------------------------------------- QL_FEATURE_DOMAIN_GENERATOR process_class @3 <000000000EE57BAC> Routine failure. Fail ------------------------------------------------------------------------------- QL_CLASS process @2 <000000000EE57A98> Routine failure. Fail ------------------------------------------------------------------------------- QL_FEATURE_DOMAIN_GENERATOR process_item @2 <000000000EE57BAC> (From QL_VISITOR) Routine failure. Fail ------------------------------------------------------------------------------- QL_FEATURE_DOMAIN_GENERATOR process_item @2 <000000000EE57BAC> (From QL_DOMAIN_GENERATOR) Routine failure. Fail ------------------------------------------------------------------------------- PROCEDURE fast_call <000000000EE5ABDC> Routine failure. Fail ------------------------------------------------------------------------------- PROCEDURE call @5 <000000000EE5ABDC> Routine failure. Fail ------------------------------------------------------------------------------- QL_CLASS_DOMAIN do_all @9 <000000000EE57B70> (From LINEAR) Routine failure. Fail ------------------------------------------------------------------------------- QL_FEATURE_DOMAIN_GENERATOR process_domain @11 <000000000EE57BAC> (From QL_DOMAIN_GENERATOR) Routine failure. Fail ------------------------------------------------------------------------------- QL_CLASS_DOMAIN new_domain @4 <000000000EE57B70> (From QL_DOMAIN) Routine failure. Fail ------------------------------------------------------------------------------- EB_EXPORTED_FORMATTER generate_result @4 <0000000010C519F8> (From EB_CLASS_FEATURE_FORMATTER) Routine failure. Fail ------------------------------------------------------------------------------- EB_EXPORTED_FORMATTER format @7 <0000000010C519F8> (From EB_CLASS_CONTENT_FORMATTER) Routine failure. Fail ------------------------------------------------------------------------------- EB_EXPORTED_FORMATTER execute @5 <0000000010C519F8> (From EB_FORMATTER) Routine failure. Fail ------------------------------------------------------------------------------- PROCEDURE fast_call <00000000128E4790> Routine failure. Fail ------------------------------------------------------------------------------- PROCEDURE call @5 <00000000128E4790> Routine failure. Fail ------------------------------------------------------------------------------- EV_NOTIFY_ACTION_SEQUENCE call @22 <00000000128E4724> (From ACTION_SEQUENCE) Routine failure. Fail ------------------------------------------------------------------------------- EV_NOTIFY_ACTION_SEQUENCE call @3 <00000000128E4724> (From EV_LITE_ACTION_SEQUENCE) Routine failure. Fail ------------------------------------------------------------------------------- SD_TOOL_BAR_RADIO_BUTTON on_pointer_release @7 <00000000128E3914> (From SD_TOOL_BAR_TOGGLE_BUTTON) Routine failure. Fail ------------------------------------------------------------------------------- SD_TOOL_BAR_RADIO_BUTTON on_pointer_release @2 <00000000128E3914> Routine failure. Fail ------------------------------------------------------------------------------- SD_TOOL_BAR on_pointer_release @10 <000000001287948C> Routine failure. Fail ------------------------------------------------------------------------------- PROCEDURE fast_call <0000000012879E4C> Routine failure. Fail ------------------------------------------------------------------------------- PROCEDURE call @5 <0000000012879E4C> Routine failure. Fail ------------------------------------------------------------------------------- EV_POINTER_BUTTON_ACTION_SEQUENCE call @22 <0000000012879DE0> (From ACTION_SEQUENCE) Routine failure. Fail ------------------------------------------------------------------------------- EV_POINTER_BUTTON_ACTION_SEQUENCE call @3 <0000000012879DE0> (From EV_LITE_ACTION_SEQUENCE) Routine failure. Fail ------------------------------------------------------------------------------- SD_DRAWING_AREA_IMP call_pointer_actions @2 <00000000128794D4> (From EV_WIDGET_IMP) Routine failure. Fail ------------------------------------------------------------------------------- SD_DRAWING_AREA_IMP on_button_up @4 <00000000128794D4> (From EV_WIDGET_IMP) Routine failure. Fail ------------------------------------------------------------------------------- SD_DRAWING_AREA_IMP on_left_button_up @2 <00000000128794D4> (From EV_WIDGET_IMP) Routine failure. Fail ------------------------------------------------------------------------------- SD_DRAWING_AREA_IMP window_process_message @12 <00000000128794D4> (From WEL_WINDOW) Routine failure. Fail ------------------------------------------------------------------------------- SD_DRAWING_AREA_IMP process_message @23 <00000000128794D4> (From WEL_COMPOSITE_WINDOW) Routine failure. Fail ------------------------------------------------------------------------------- WEL_DISPATCHER window_procedure @10 <0000000010A01AB0> (From WEL_ABSTRACT_DISPATCHER) Routine failure. Fail ------------------------------------------------------------------------------- WEL_MSG cwin_dispatch_message <0000000010A01CCC> Routine failure. Fail ------------------------------------------------------------------------------- WEL_MSG dispatch @1 <0000000010A01CCC> Routine failure. Fail ------------------------------------------------------------------------------- EV_APPLICATION_IMP process_message @11 <0000000010A01318> Routine failure. Fail ------------------------------------------------------------------------------- EV_APPLICATION_IMP process_underlying_toolkit_event_queue @7 <0000000010A01318> Routine failure. Fail ------------------------------------------------------------------------------- EV_APPLICATION_IMP process_event_queue @2 <0000000010A01318> (From EV_APPLICATION_I) Routine failure. Fail ------------------------------------------------------------------------------- EV_APPLICATION_IMP launch @3 <0000000010A01318> (From EV_APPLICATION_I) Routine failure. Fail ------------------------------------------------------------------------------- EV_APPLICATION launch @4 <0000000010A012F4> Routine failure. Fail ------------------------------------------------------------------------------- ES_GRAPHIC make @4 <0000000010A01294> Routine failure. Fail ------------------------------------------------------------------------------- EB_KERNEL make @6 <0000000010A0124C> Routine failure. Fail ------------------------------------------------------------------------------- EB_KERNEL root's creation <0000000010A0124C> Routine failure. Exit ------------------------------------------------------------------------------- Call stack: ObjectClassRoutine ------------------ [0x107C209C] FIXED_LIST item ( @ 3 ) [0x107C2074] QL_FEATURE_DOMAIN_GENERATOR record_ancestors_of_class (From QL_DOMAIN_GENERATOR) ( @ 6 ) [0x107C2074] QL_FEATURE_DOMAIN_GENERATOR process_feature_from_class (From QL_DOMAIN_GENERATOR) ( @ 16 ) [0x107C2074] QL_FEATURE_DOMAIN_GENERATOR process_class ( @ 3 ) [0x107C20B4] QL_CLASS process ( @ 2 ) [0x107C2074] QL_FEATURE_DOMAIN_GENERATOR process_item (From QL_VISITOR) ( @ 2 ) [0x107C2074] QL_FEATURE_DOMAIN_GENERATOR process_item (From QL_DOMAIN_GENERATOR) ( @ 2 ) [0x107C20BC] PROCEDURE fast_call ( @ 0 ) [0x107C20BC] PROCEDURE call ( @ 5 ) [0x107C20A8] QL_CLASS_DOMAIN do_all (From LINEAR) ( @ 9 ) [0x107C2074] QL_FEATURE_DOMAIN_GENERATOR process_domain (From QL_DOMAIN_GENERATOR) ( @ 11 ) [0x107C20A8] QL_CLASS_DOMAIN new_domain (From QL_DOMAIN) ( @ 4 ) [0x107C20C0] EB_EXPORTED_FORMATTER generate_result (From EB_CLASS_FEATURE_FORMATTER) ( @ 4 ) [0x107C20C0] EB_EXPORTED_FORMATTER format (From EB_CLASS_CONTENT_FORMATTER) ( @ 7 ) [0x107C20C0] EB_EXPORTED_FORMATTER execute (From EB_FORMATTER) ( @ 5 ) [0x107C2088] PROCEDURE fast_call ( @ 0 ) [0x107C2088] PROCEDURE call ( @ 5 ) [0x107C207C] EV_NOTIFY_ACTION_SEQUENCE call (From ACTION_SEQUENCE) ( @ 22 ) [0x107C207C] EV_NOTIFY_ACTION_SEQUENCE call (From EV_LITE_ACTION_SEQUENCE) ( @ 3 ) [0x107C20AC] SD_TOOL_BAR_RADIO_BUTTON on_pointer_release (From SD_TOOL_BAR_TOGGLE_BUTTON) ( @ 7 ) [0x107C20AC] SD_TOOL_BAR_RADIO_BUTTON on_pointer_release ( @ 2 ) [0x107C205C] SD_TOOL_BAR on_pointer_release ( @ 10 ) [0x107C20A0] PROCEDURE fast_call ( @ 0 ) [0x107C20A0] PROCEDURE call ( @ 5 ) [0x107C208C] EV_POINTER_BUTTON_ACTION_SEQUENCE call (From ACTION_SEQUENCE) ( @ 22 ) [0x107C208C] EV_POINTER_BUTTON_ACTION_SEQUENCE call (From EV_LITE_ACTION_SEQUENCE) ( @ 3 ) [0x107C2060] SD_DRAWING_AREA_IMP call_pointer_actions (From EV_WIDGET_IMP) ( @ 2 ) [0x107C2060] SD_DRAWING_AREA_IMP on_button_up (From EV_WIDGET_IMP) ( @ 4 ) [0x107C2060] SD_DRAWING_AREA_IMP on_left_button_up (From EV_WIDGET_IMP) ( @ 2 ) [0x107C2060] SD_DRAWING_AREA_IMP window_process_message (From WEL_WINDOW) ( @ 12 ) [0x107C2060] SD_DRAWING_AREA_IMP process_message (From WEL_COMPOSITE_WINDOW) ( @ 23 ) [0x107C2084] WEL_DISPATCHER window_procedure (From WEL_ABSTRACT_DISPATCHER) ( @ 10 ) [0x107C2094] WEL_MSG cwin_dispatch_message ( @ 0 ) [0x107C2094] WEL_MSG dispatch ( @ 1 ) [0x107C2090] EV_APPLICATION_IMP process_message ( @ 11 ) [0x107C2090] EV_APPLICATION_IMP process_underlying_toolkit_event_queue ( @ 7 ) [0x107C2090] EV_APPLICATION_IMP process_event_queue (From EV_APPLICATION_I) ( @ 2 ) [0x107C2090] EV_APPLICATION_IMP launch (From EV_APPLICATION_I) ( @ 3 ) [0x107C206C] EV_APPLICATION launch ( @ 4 ) [0x107C2068] ES_GRAPHIC make ( @ 4 ) [0x107C2080] EB_KERNEL make ( @ 6 )