Zhiyi Zhang (@zhiyi) commented about dlls/comctl32/tests/rebar.c:
+ rbi.cyMinChild = rbi.cxMinChild; + rbi.hwndChild = build_toolbar(1, hRebar); + rbi.fStyle = RBBS_USECHEVRON | RBBS_NOGRIPPER; + SendMessageA(hRebar, RB_INSERTBANDA, 0, (LPARAM)&rbi); + SendMessageA(hRebar, RB_INSERTBANDA, 1, (LPARAM)&rbi); + + SetRectEmpty(&g_chevron_rect); + SendMessageA(hRebar, RB_PUSHCHEVRON, 0, 0); + ok(!IsRectEmpty(&g_chevron_rect), "Unexpected empty chevron rect\n"); + + /* increase band width to make child rect width more then ideal value to hide chevron */ + rbi.fMask = RBBIM_SIZE; + rbi.cx = rbi.cx + 1; + SendMessageA(hRebar, RB_SETBANDINFOA, 0, (LPARAM)&rbi); + + SetRect(&g_chevron_rect, 1, 1, 1, 1); You should set a non-empty rect here. For example, "SetRect(&g_chevron_rect, 1, 1, 2, 2);". (1,1,1,1) is an empty rectangle. See the implementation of IsRectEmpty().
-- https://gitlab.winehq.org/wine/wine/-/merge_requests/6075#note_79084