WS_VSCROLL，CreateWindow风格的作品，SetWindowLong不(WS_VSCROLL, CreateWindow style works, SetWindowLong doesnt)

 当我做 
 
wnd = CreateWindow("EDIT", 0,
    WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_HSCROLL | ES_MULTILINE | 
    ES_AUTOVSCROLL | ES_AUTOHSCROLL | ES_WANTRETURN,
    x, y, w, h,
    parentWnd,
    NULL, NULL, NULL);
 
 一切都很好，但是如果我删除WS_VSCROLL和WS_HSCROLL然后执行下面，我不明白他们有不正确的窗口。 为什么？ 如果WS_VSCROLL和WS_HSCROLL都丢失，我不仅会得到不正确的窗口，而且它也不可用 
 
style = WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_HSCROLL | ES_MULTILINE |
    ES_AUTOVSCROLL | ES_AUTOHSCROLL | ES_WANTRETURN;
SetWindowLong(wnd, GWL_STYLE, style);

When i do 
 
wnd = CreateWindow("EDIT", 0,
    WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_HSCROLL | ES_MULTILINE | 
    ES_AUTOVSCROLL | ES_AUTOHSCROLL | ES_WANTRETURN,
    x, y, w, h,
    parentWnd,
    NULL, NULL, NULL);
 
everything is fine, however if i remove the WS_VSCROLL and WS_HSCROLL then do the below, i do not get them thus have incorrect window. Why? Not only do i get an incorrect window it is unusable if both WS_VSCROLL and WS_HSCROLL are missing
 
style = WS_CHILD | WS_VISIBLE | WS_VSCROLL | WS_HSCROLL | ES_MULTILINE |
    ES_AUTOVSCROLL | ES_AUTOHSCROLL | ES_WANTRETURN;
SetWindowLong(wnd, GWL_STYLE, style);

原文：https://stackoverflow.com/questions/285587