A number of "new" widgets (efl_ui_XYZ) have been implemented using edje part names like 'indicator' or 'first'. These part names must be namespaced like 'efl.indicator' or 'efl.first'.
Problematic cases can be found with something like grep -nw 'efl_part' src/lib/elementary/*c|grep '"'|grep -v '"elm.\|"efl.':
src/lib/elementary/efl_ui_panes.c:218: first_content = efl_content_get(efl_part(obj, "first")); src/lib/elementary/efl_ui_panes.c:219: second_content = efl_content_get(efl_part(obj, "second")); src/lib/elementary/efl_ui_popup_alert.c:34: efl_text_set(efl_part(efl_super(obj, MY_CLASS), "title"), label); src/lib/elementary/efl_ui_popup_alert_scroll.c:165: efl_content_set(efl_part(pd->scroller, "default"), pd->content); src/lib/elementary/efl_ui_popup_alert_scroll.c:196: return efl_content_unset(efl_part(pd->scroller, "default")); src/lib/elementary/efl_ui_popup_alert_text.c:201: efl_content_set(efl_part(pd->scroller, "default"), pd->message); src/lib/elementary/efl_ui_slider.c:1192: efl_ui_format_string_set(efl_part(obj, "indicator"), "%0.2f"); src/lib/elementary/efl_ui_slider.c:1490: efl_ui_format_cb_set(efl_part(pd->obj, "indicator"), pd->obj, _indi_default_format_cb, _indi_default_format_free_cb); src/lib/elementary/efl_ui_slider.c:1753: efl_ui_format_string_set(efl_part(obj, "indicator"), indicator); src/lib/elementary/efl_ui_slider.c:1759: return efl_ui_format_string_get(efl_part(obj, "indicator")); src/lib/elementary/efl_ui_slider.c:1770: efl_ui_format_cb_set(efl_part(obj, "indicator"), sfwd, src/lib/elementary/efl_ui_slider.c:1778: efl_ui_slider_part_indicator_visible_mode_set(efl_part(obj, "indicator"), src/lib/elementary/efl_ui_slider.c:1786: return (efl_ui_slider_part_indicator_visible_mode_get(efl_part(obj, "indicator")) src/lib/elementary/efl_ui_slider.c:1827: efl_ui_slider_part_indicator_visible_mode_set(efl_part(obj, "indicator"), indicator_visible_mode); src/lib/elementary/efl_ui_slider.c:1833: return efl_ui_slider_part_indicator_visible_mode_get(efl_part(obj, "indicator"));
These cases must all be namespaced before the release, and further patch submissions which contain non-namespaced part names must be rejected.